<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/drivers/gpu/vga, branch v4.11-rc6</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>sched/headers: Prepare to move signal wakeup &amp; sigpending methods from &lt;linux/sched.h&gt; into &lt;linux/sched/signal.h&gt;</title>
<updated>2017-03-02T07:42:32+00:00</updated>
<author>
<name>Ingo Molnar</name>
<email>mingo@kernel.org</email>
</author>
<published>2017-02-02T18:15:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=174cd4b1e5fbd0d74c68cf3a74f5bd4923485512'/>
<id>174cd4b1e5fbd0d74c68cf3a74f5bd4923485512</id>
<content type='text'>
Fix up affected files that include this signal functionality via sched.h.

Acked-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Mike Galbraith &lt;efault@gmx.de&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Fix up affected files that include this signal functionality via sched.h.

Acked-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Mike Galbraith &lt;efault@gmx.de&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>vgaarb: use valid dev pointer in vgaarb_info()</title>
<updated>2016-11-22T15:40:35+00:00</updated>
<author>
<name>Arnd Bergmann</name>
<email>arnd@arndb.de</email>
</author>
<published>2016-11-22T14:34:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=ed2ab35ef1a1f7d42b5dc0d130d359cc0f5e3d9d'/>
<id>ed2ab35ef1a1f7d42b5dc0d130d359cc0f5e3d9d</id>
<content type='text'>
We now pass the device to the debug messages, but on non-x86,
this is an invalid pointer in vga_arb_device_init:

drivers/gpu/vga/vgaarb.c: In function 'vga_arb_device_init':
drivers/gpu/vga/vgaarb.c:1467:4: error: 'dev' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This moves the initialization of the dev pointer outside of the
architecture #ifdef.

Fixes: a75d68f62106 ("vgaarb: Use dev_printk() when possible")
Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/20161122143445.1896558-1-arnd@arndb.de
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We now pass the device to the debug messages, but on non-x86,
this is an invalid pointer in vga_arb_device_init:

drivers/gpu/vga/vgaarb.c: In function 'vga_arb_device_init':
drivers/gpu/vga/vgaarb.c:1467:4: error: 'dev' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This moves the initialization of the dev pointer outside of the
architecture #ifdef.

Fixes: a75d68f62106 ("vgaarb: Use dev_printk() when possible")
Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/20161122143445.1896558-1-arnd@arndb.de
</pre>
</div>
</content>
</entry>
<entry>
<title>vgaarb: Downgrade userspace-triggerable messages to debug</title>
<updated>2016-11-18T15:29:52+00:00</updated>
<author>
<name>Bjorn Helgaas</name>
<email>bhelgaas@google.com</email>
</author>
<published>2016-11-18T14:11:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=cf590b8732701778c067ed4dff579fa2d7ac251e'/>
<id>cf590b8732701778c067ed4dff579fa2d7ac251e</id>
<content type='text'>
To avoid userspace-triggerable dmesg spam, downgrade messages in the sysfs
write parsing code to debug level.

Signed-off-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/20161118141158.32415.71438.stgit@bhelgaas-glaptop.roam.corp.google.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
To avoid userspace-triggerable dmesg spam, downgrade messages in the sysfs
write parsing code to debug level.

Signed-off-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/20161118141158.32415.71438.stgit@bhelgaas-glaptop.roam.corp.google.com
</pre>
</div>
</content>
</entry>
<entry>
<title>vgaarb: Use dev_printk() when possible</title>
<updated>2016-11-18T09:43:20+00:00</updated>
<author>
<name>Bjorn Helgaas</name>
<email>bhelgaas@google.com</email>
</author>
<published>2016-11-17T17:47:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a75d68f62106fe66c4b8b96c0ee7155bdafc6f06'/>
<id>a75d68f62106fe66c4b8b96c0ee7155bdafc6f06</id>
<content type='text'>
Use dev_printk() when possible.  This makes messages more consistent with
other device-related messages and, in some cases, adds useful information.
This changes messages like this:

  vgaarb: failed to allocate pci device
  vgaarb: setting as boot device: PCI:0000:01:00.0
  vgaarb: device added: PCI:0000:01:00.0,decodes=io+mem,owns=io+mem,locks=none
  vgaarb: bridge control possible 0000:01:00.0

to this:

  pci 0000:01:00.0: vgaarb: failed to allocate VGA arbiter data
  pci 0000:01:00.0: vgaarb: setting as boot VGA device
  pci 0000:01:00.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
  pci 0000:01:00.0: vgaarb: bridge control possible

No functional change intended.

Signed-off-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/20161117174758.16810.67625.stgit@bhelgaas-glaptop.roam.corp.google.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Use dev_printk() when possible.  This makes messages more consistent with
other device-related messages and, in some cases, adds useful information.
This changes messages like this:

  vgaarb: failed to allocate pci device
  vgaarb: setting as boot device: PCI:0000:01:00.0
  vgaarb: device added: PCI:0000:01:00.0,decodes=io+mem,owns=io+mem,locks=none
  vgaarb: bridge control possible 0000:01:00.0

to this:

  pci 0000:01:00.0: vgaarb: failed to allocate VGA arbiter data
  pci 0000:01:00.0: vgaarb: setting as boot VGA device
  pci 0000:01:00.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
  pci 0000:01:00.0: vgaarb: bridge control possible

No functional change intended.

Signed-off-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/20161117174758.16810.67625.stgit@bhelgaas-glaptop.roam.corp.google.com
</pre>
</div>
</content>
</entry>
<entry>
<title>drivers/gpu/vga: allocate vga_arb_write() buffer on stack</title>
<updated>2016-10-17T06:21:14+00:00</updated>
<author>
<name>Dmitry Vyukov</name>
<email>dvyukov@google.com</email>
</author>
<published>2016-10-14T13:22:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=49521b13cbc02aff9ac1fff8d425055cc86cef08'/>
<id>49521b13cbc02aff9ac1fff8d425055cc86cef08</id>
<content type='text'>
Size of kmalloc() in vga_arb_write() is controlled by user.
Too large kmalloc() size triggers WARNING message on console.
Allocate the buffer on stack to avoid the WARNING.
The string must be small (e.g "target PCI:domain:bus:dev.fn").

Signed-off-by: Dmitry Vyukov &lt;dvyukov@google.com&gt;
Reviewed-by: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Cc: Dave Airlie &lt;airlied@gmail.com&gt;
Cc: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Cc: dri-devel@lists.freedesktop.org
Cc: syzkaller@googlegroups.com
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/1476451342-146510-1-git-send-email-dvyukov@google.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Size of kmalloc() in vga_arb_write() is controlled by user.
Too large kmalloc() size triggers WARNING message on console.
Allocate the buffer on stack to avoid the WARNING.
The string must be small (e.g "target PCI:domain:bus:dev.fn").

Signed-off-by: Dmitry Vyukov &lt;dvyukov@google.com&gt;
Reviewed-by: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Cc: Dave Airlie &lt;airlied@gmail.com&gt;
Cc: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Cc: dri-devel@lists.freedesktop.org
Cc: syzkaller@googlegroups.com
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/1476451342-146510-1-git-send-email-dvyukov@google.com
</pre>
</div>
</content>
</entry>
<entry>
<title>vgaarbiter: rst-ifiy and polish kerneldoc</title>
<updated>2016-08-16T16:49:56+00:00</updated>
<author>
<name>Daniel Vetter</name>
<email>daniel.vetter@ffwll.ch</email>
</author>
<published>2016-08-12T20:48:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=b754b35b089ddfea3ff7b9b1d2e99e61d726d177'/>
<id>b754b35b089ddfea3ff7b9b1d2e99e61d726d177</id>
<content type='text'>
Move the documentation into Documentation/gpu, link it up and pull in
the kernel doc.

No actual text changes except that I did polish the kerneldoc a bit,
especially for vga_client_register().

v2: Remove some rst from vga-switcheroo.rst that I don't understand,
but which seems to be the reason why the new vgaarbiter.rst sometimes
drops out of the sidebar index.

v3: Drop one level of headings and clarify the vgaarb one a bit.

v4: Fix some typos (Sean).

Cc: Jonathan Corbet &lt;corbet@lwn.net&gt;
Cc: linux-doc@vger.kernel.org
Cc: Sean Paul &lt;seanpaul@chromium.org&gt;
Reviewed-by: Sean Paul &lt;seanpaul@chromium.org&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@intel.com&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/1471034937-651-20-git-send-email-daniel.vetter@ffwll.ch
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Move the documentation into Documentation/gpu, link it up and pull in
the kernel doc.

No actual text changes except that I did polish the kerneldoc a bit,
especially for vga_client_register().

v2: Remove some rst from vga-switcheroo.rst that I don't understand,
but which seems to be the reason why the new vgaarbiter.rst sometimes
drops out of the sidebar index.

v3: Drop one level of headings and clarify the vgaarb one a bit.

v4: Fix some typos (Sean).

Cc: Jonathan Corbet &lt;corbet@lwn.net&gt;
Cc: linux-doc@vger.kernel.org
Cc: Sean Paul &lt;seanpaul@chromium.org&gt;
Reviewed-by: Sean Paul &lt;seanpaul@chromium.org&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@intel.com&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/1471034937-651-20-git-send-email-daniel.vetter@ffwll.ch
</pre>
</div>
</content>
</entry>
<entry>
<title>vga_switcheroo: Sphinxify docs</title>
<updated>2016-07-12T14:14:36+00:00</updated>
<author>
<name>Lukas Wunner</name>
<email>lukas@wunner.de</email>
</author>
<published>2016-07-11T08:22:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=fb001dfd7e773d86b5dcd2050995a5fee301eab1'/>
<id>fb001dfd7e773d86b5dcd2050995a5fee301eab1</id>
<content type='text'>
Fix up formatting glitches remaining after the automatic rst conversion.

Cc: Jonathan Corbet &lt;corbet@lwn.net&gt;
Cc: Jani Nikula &lt;jani.nikula@intel.com&gt;
Signed-off-by: Lukas Wunner &lt;lukas@wunner.de&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/3a369602ae35fdbf5e4a12f7e172088c89fa27bb.1468225027.git.lukas@wunner.de
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Fix up formatting glitches remaining after the automatic rst conversion.

Cc: Jonathan Corbet &lt;corbet@lwn.net&gt;
Cc: Jani Nikula &lt;jani.nikula@intel.com&gt;
Signed-off-by: Lukas Wunner &lt;lukas@wunner.de&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/3a369602ae35fdbf5e4a12f7e172088c89fa27bb.1468225027.git.lukas@wunner.de
</pre>
</div>
</content>
</entry>
<entry>
<title>vga_switcheroo: Support deferred probing of audio clients</title>
<updated>2016-05-31T11:16:22+00:00</updated>
<author>
<name>Lukas Wunner</name>
<email>lukas@wunner.de</email>
</author>
<published>2016-05-31T09:13:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a345918d6ee69076fea098cd317385937402c85b'/>
<id>a345918d6ee69076fea098cd317385937402c85b</id>
<content type='text'>
Daniel Vetter pointed out that vga_switcheroo_client_probe_defer() could
be needed by audio clients as well. To avoid mistakes when someone adds
conditions for these in the future, constrain the single existing
condition to VGA clients by checking for PCI_BASE_CLASS_DISPLAY. This
encompasses both PCI_CLASS_DISPLAY_VGA as well as PCI_CLASS_DISPLAY_3D,
which is used by some Nvidia Optimus GPUs.

Any future checks for audio clients should then be constrained to
PCI_BASE_CLASS_MULTIMEDIA.

v6: Spun out from commit introducing vga_switcheroo_client_probe_defer()
    to keep it a pure refactoring change. (Emil Velikov, Jani Nikula)

Cc: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Cc: Emil Velikov &lt;emil.l.velikov@gmail.com&gt;
Cc: Jani Nikula &lt;jani.nikula@linux.intel.com&gt;
Signed-off-by: Lukas Wunner &lt;lukas@wunner.de&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/358d58490eb9dda5f270d844b0dce511a2a20828.1464685538.git.lukas@wunner.de
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Daniel Vetter pointed out that vga_switcheroo_client_probe_defer() could
be needed by audio clients as well. To avoid mistakes when someone adds
conditions for these in the future, constrain the single existing
condition to VGA clients by checking for PCI_BASE_CLASS_DISPLAY. This
encompasses both PCI_CLASS_DISPLAY_VGA as well as PCI_CLASS_DISPLAY_3D,
which is used by some Nvidia Optimus GPUs.

Any future checks for audio clients should then be constrained to
PCI_BASE_CLASS_MULTIMEDIA.

v6: Spun out from commit introducing vga_switcheroo_client_probe_defer()
    to keep it a pure refactoring change. (Emil Velikov, Jani Nikula)

Cc: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Cc: Emil Velikov &lt;emil.l.velikov@gmail.com&gt;
Cc: Jani Nikula &lt;jani.nikula@linux.intel.com&gt;
Signed-off-by: Lukas Wunner &lt;lukas@wunner.de&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/358d58490eb9dda5f270d844b0dce511a2a20828.1464685538.git.lukas@wunner.de
</pre>
</div>
</content>
</entry>
<entry>
<title>vga_switcheroo: Add helper for deferred probing</title>
<updated>2016-05-31T11:15:57+00:00</updated>
<author>
<name>Lukas Wunner</name>
<email>lukas@wunner.de</email>
</author>
<published>2016-05-31T09:13:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=b00e5334ab1bb2e41187fb964a1a2304871fb4ff'/>
<id>b00e5334ab1bb2e41187fb964a1a2304871fb4ff</id>
<content type='text'>
So far we've got one condition when DRM drivers need to defer probing
on a dual GPU system and it's coded separately into each of the relevant
drivers. As suggested by Daniel Vetter, deduplicate that code in the
drivers and move it to a new vga_switcheroo helper. This yields better
encapsulation of concepts and lets us add further checks in a central
place. (The existing check pertains to pre-retina MacBook Pros and an
additional check is expected to be needed for retinas.)

One might be tempted to check deferred probing conditions in
vga_switcheroo_register_client(), but this is usually called fairly late
during driver load. The GPU is fully brought up and ready for switching
at that point. On boot the -&gt;probe hook is potentially called dozens of
times until it finally succeeds, and each time we'd repeat bringup and
teardown of the GPU, lengthening boot time considerably and cluttering
logfiles. A separate helper is therefore needed which can be called
right at the beginning of the -&gt;probe hook.

Note that amdgpu currently does not call this helper as the AMD GPUs
built into MacBook Pros are only supported by radeon so far.

v2: This helper could eventually be used by audio clients as well,
    so rephrase kerneldoc to refer to "client" instead of "GPU"
    and move the single existing check in an if block specific
    to PCI_CLASS_DISPLAY_VGA devices. Move documentation on
    that check from kerneldoc to a comment. (Daniel Vetter)

v3: Mandate in kerneldoc that registration of client shall only
    happen after calling this helper. (Daniel Vetter)

v4: Rebase on 412c8f7de011 ("drm/radeon: Return -EPROBE_DEFER when
    amdkfd not loaded")

v5: Some Optimus GPUs use PCI_CLASS_DISPLAY_3D, make sure those are
    matched as well. (Emil Velikov)

v6: The if-condition referring to PCI_BASE_CLASS_DISPLAY may be
    considered a functional change. Move to a separate commit to
    keep this a pure refactoring change. (Emil Velikov, Jani Nikula)

Cc: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Cc: Ben Skeggs &lt;bskeggs@redhat.com&gt;
Cc: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Lukas Wunner &lt;lukas@wunner.de&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/575885fd440c2b13c3f19ddf44360cfbbff35f50.1464685538.git.lukas@wunner.de
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
So far we've got one condition when DRM drivers need to defer probing
on a dual GPU system and it's coded separately into each of the relevant
drivers. As suggested by Daniel Vetter, deduplicate that code in the
drivers and move it to a new vga_switcheroo helper. This yields better
encapsulation of concepts and lets us add further checks in a central
place. (The existing check pertains to pre-retina MacBook Pros and an
additional check is expected to be needed for retinas.)

One might be tempted to check deferred probing conditions in
vga_switcheroo_register_client(), but this is usually called fairly late
during driver load. The GPU is fully brought up and ready for switching
at that point. On boot the -&gt;probe hook is potentially called dozens of
times until it finally succeeds, and each time we'd repeat bringup and
teardown of the GPU, lengthening boot time considerably and cluttering
logfiles. A separate helper is therefore needed which can be called
right at the beginning of the -&gt;probe hook.

Note that amdgpu currently does not call this helper as the AMD GPUs
built into MacBook Pros are only supported by radeon so far.

v2: This helper could eventually be used by audio clients as well,
    so rephrase kerneldoc to refer to "client" instead of "GPU"
    and move the single existing check in an if block specific
    to PCI_CLASS_DISPLAY_VGA devices. Move documentation on
    that check from kerneldoc to a comment. (Daniel Vetter)

v3: Mandate in kerneldoc that registration of client shall only
    happen after calling this helper. (Daniel Vetter)

v4: Rebase on 412c8f7de011 ("drm/radeon: Return -EPROBE_DEFER when
    amdkfd not loaded")

v5: Some Optimus GPUs use PCI_CLASS_DISPLAY_3D, make sure those are
    matched as well. (Emil Velikov)

v6: The if-condition referring to PCI_BASE_CLASS_DISPLAY may be
    considered a functional change. Move to a separate commit to
    keep this a pure refactoring change. (Emil Velikov, Jani Nikula)

Cc: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Cc: Ben Skeggs &lt;bskeggs@redhat.com&gt;
Cc: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Lukas Wunner &lt;lukas@wunner.de&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/575885fd440c2b13c3f19ddf44360cfbbff35f50.1464685538.git.lukas@wunner.de
</pre>
</div>
</content>
</entry>
<entry>
<title>vga_switcheroo: Add support for switching only the DDC</title>
<updated>2016-02-09T10:21:07+00:00</updated>
<author>
<name>Lukas Wunner</name>
<email>lukas@wunner.de</email>
</author>
<published>2016-01-11T19:09:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=e4cb81d7e49c806fa557cf0ff4f3f40bd7a9cb7c'/>
<id>e4cb81d7e49c806fa557cf0ff4f3f40bd7a9cb7c</id>
<content type='text'>
Originally by Seth Forshee &lt;seth.forshee@canonical.com&gt;, 2012-10-04:
    During graphics driver initialization it's useful to be able to mux
    only the DDC to the inactive client in order to read the EDID. Add
    a switch_ddc callback to allow capable handlers to provide this
    functionality, and add vga_switcheroo_switch_ddc() to allow DRM
    to mux only the DDC.

Modified by Dave Airlie &lt;airlied@gmail.com&gt;, 2012-12-22:
    I can't figure out why I didn't like this, but I rewrote this [...]
    to lock/unlock the ddc lines [...]. I think I'd prefer something
    like that otherwise the interface got really ugly.

Modified by Lukas Wunner &lt;lukas@wunner.de&gt;, 2015-04 - 2015-10:
    Change semantics of -&gt;switch_ddc handler callback to return previous
    DDC owner. Original version tried to determine previous DDC owner
    with find_active_client() but this fails if the inactive client
    registers before the active client.

    Don't lock vgasr_mutex in _lock_ddc() / _unlock_ddc(), it can cause
    deadlocks because (a) during switch (with vgasr_mutex already held),
    GPU is woken and probes its outputs, tries to re-acquire vgasr_mutex
    to lock DDC lines; (b) Likewise during switch, GPU is suspended and
    calls cancel_delayed_work_sync() to stop output polling, if poll
    task is running at this moment we may wait forever for it to finish.

    Instead, lock mux_hw_lock when unregistering the handler because
    the only reason why we'd want to lock vgasr_mutex in _lock_ddc() /
    _unlock_ddc() is to block the handler from disappearing while DDC
    lines are switched.

    Also acquire mux_hw_lock in stage2 to avoid race condition where
    reading the EDID and switching happens simultaneously. Likewise on
    MIGD / MDIS commands and on runtime suspend.

    v2.1: Overhaul locking, squash commits (Daniel Vetter)

    v2.2: Readability improvements (Thierry Reding)

    v2.3: Overhaul locking once more

    v2.4: Retain semantics of -&gt;switchto handler callback to switch all
          pins, including DDC (Daniel Vetter)

    v5:   Rename ddc_lock to mux_hw_lock: Since we acquire this both
          when calling -&gt;switch_ddc and -&gt;switchto, it protects not just
          access to the DDC lines but to the mux in general. This is in
          line with the DRM convention to use low-level locks to avoid
          concurrent hw access (e.g. i2c, dp_aux) which are often called
          hw_lock (Daniel Vetter)

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115
Tested-by: Lukas Wunner &lt;lukas@wunner.de&gt;
    [MBP  9,1 2012  intel IVB + nvidia GK107  pre-retina  15"]
Cc: Seth Forshee &lt;seth.forshee@canonical.com&gt;
Cc: Dave Airlie &lt;airlied@gmail.com&gt;
Signed-off-by: Lukas Wunner &lt;lukas@wunner.de&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/e81ae9722b84c5ed591805fee3ea6dbf5dc6c4b3.1452525860.git.lukas@wunner.de
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Originally by Seth Forshee &lt;seth.forshee@canonical.com&gt;, 2012-10-04:
    During graphics driver initialization it's useful to be able to mux
    only the DDC to the inactive client in order to read the EDID. Add
    a switch_ddc callback to allow capable handlers to provide this
    functionality, and add vga_switcheroo_switch_ddc() to allow DRM
    to mux only the DDC.

Modified by Dave Airlie &lt;airlied@gmail.com&gt;, 2012-12-22:
    I can't figure out why I didn't like this, but I rewrote this [...]
    to lock/unlock the ddc lines [...]. I think I'd prefer something
    like that otherwise the interface got really ugly.

Modified by Lukas Wunner &lt;lukas@wunner.de&gt;, 2015-04 - 2015-10:
    Change semantics of -&gt;switch_ddc handler callback to return previous
    DDC owner. Original version tried to determine previous DDC owner
    with find_active_client() but this fails if the inactive client
    registers before the active client.

    Don't lock vgasr_mutex in _lock_ddc() / _unlock_ddc(), it can cause
    deadlocks because (a) during switch (with vgasr_mutex already held),
    GPU is woken and probes its outputs, tries to re-acquire vgasr_mutex
    to lock DDC lines; (b) Likewise during switch, GPU is suspended and
    calls cancel_delayed_work_sync() to stop output polling, if poll
    task is running at this moment we may wait forever for it to finish.

    Instead, lock mux_hw_lock when unregistering the handler because
    the only reason why we'd want to lock vgasr_mutex in _lock_ddc() /
    _unlock_ddc() is to block the handler from disappearing while DDC
    lines are switched.

    Also acquire mux_hw_lock in stage2 to avoid race condition where
    reading the EDID and switching happens simultaneously. Likewise on
    MIGD / MDIS commands and on runtime suspend.

    v2.1: Overhaul locking, squash commits (Daniel Vetter)

    v2.2: Readability improvements (Thierry Reding)

    v2.3: Overhaul locking once more

    v2.4: Retain semantics of -&gt;switchto handler callback to switch all
          pins, including DDC (Daniel Vetter)

    v5:   Rename ddc_lock to mux_hw_lock: Since we acquire this both
          when calling -&gt;switch_ddc and -&gt;switchto, it protects not just
          access to the DDC lines but to the mux in general. This is in
          line with the DRM convention to use low-level locks to avoid
          concurrent hw access (e.g. i2c, dp_aux) which are often called
          hw_lock (Daniel Vetter)

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115
Tested-by: Lukas Wunner &lt;lukas@wunner.de&gt;
    [MBP  9,1 2012  intel IVB + nvidia GK107  pre-retina  15"]
Cc: Seth Forshee &lt;seth.forshee@canonical.com&gt;
Cc: Dave Airlie &lt;airlied@gmail.com&gt;
Signed-off-by: Lukas Wunner &lt;lukas@wunner.de&gt;
Signed-off-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt;
Link: http://patchwork.freedesktop.org/patch/msgid/e81ae9722b84c5ed591805fee3ea6dbf5dc6c4b3.1452525860.git.lukas@wunner.de
</pre>
</div>
</content>
</entry>
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