<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/drivers/firewire, branch v4.8-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>treewide: replace dev-&gt;trans_start update with helper</title>
<updated>2016-05-04T18:16:49+00:00</updated>
<author>
<name>Florian Westphal</name>
<email>fw@strlen.de</email>
</author>
<published>2016-05-03T14:33:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=860e9538a9482bb84589f7d0718a7e6d0a944d58'/>
<id>860e9538a9482bb84589f7d0718a7e6d0a944d58</id>
<content type='text'>
Replace all trans_start updates with netif_trans_update helper.
change was done via spatch:

struct net_device *d;
@@
- d-&gt;trans_start = jiffies
+ netif_trans_update(d)

Compile tested only.

Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: linux-xtensa@linux-xtensa.org
Cc: linux1394-devel@lists.sourceforge.net
Cc: linux-rdma@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: MPT-FusionLinux.pdl@broadcom.com
Cc: linux-scsi@vger.kernel.org
Cc: linux-can@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linux-omap@vger.kernel.org
Cc: linux-hams@vger.kernel.org
Cc: linux-usb@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: devel@driverdev.osuosl.org
Cc: b.a.t.m.a.n@lists.open-mesh.org
Cc: linux-bluetooth@vger.kernel.org
Signed-off-by: Florian Westphal &lt;fw@strlen.de&gt;
Acked-by: Felipe Balbi &lt;felipe.balbi@linux.intel.com&gt;
Acked-by: Mugunthan V N &lt;mugunthanvnm@ti.com&gt;
Acked-by: Antonio Quartulli &lt;a@unstable.cc&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Replace all trans_start updates with netif_trans_update helper.
change was done via spatch:

struct net_device *d;
@@
- d-&gt;trans_start = jiffies
+ netif_trans_update(d)

Compile tested only.

Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: linux-xtensa@linux-xtensa.org
Cc: linux1394-devel@lists.sourceforge.net
Cc: linux-rdma@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: MPT-FusionLinux.pdl@broadcom.com
Cc: linux-scsi@vger.kernel.org
Cc: linux-can@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linux-omap@vger.kernel.org
Cc: linux-hams@vger.kernel.org
Cc: linux-usb@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: devel@driverdev.osuosl.org
Cc: b.a.t.m.a.n@lists.open-mesh.org
Cc: linux-bluetooth@vger.kernel.org
Signed-off-by: Florian Westphal &lt;fw@strlen.de&gt;
Acked-by: Felipe Balbi &lt;felipe.balbi@linux.intel.com&gt;
Acked-by: Mugunthan V N &lt;mugunthanvnm@ti.com&gt;
Acked-by: Antonio Quartulli &lt;a@unstable.cc&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'firewire-update2' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394</title>
<updated>2016-03-25T15:52:25+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2016-03-25T15:52:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=3b3b3bd97788e1f574c71f865d8465b00a6b8708'/>
<id>3b3b3bd97788e1f574c71f865d8465b00a6b8708</id>
<content type='text'>
Pull firewire leftover from Stefan Richter:
 "Occurrences of timeval were supposed to be eliminated last round, now
  remove a last forgotten one"

* tag 'firewire-update2' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: nosy: Replace timeval with timespec64
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull firewire leftover from Stefan Richter:
 "Occurrences of timeval were supposed to be eliminated last round, now
  remove a last forgotten one"

* tag 'firewire-update2' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: nosy: Replace timeval with timespec64
</pre>
</div>
</content>
</entry>
<entry>
<title>firewire: use in_compat_syscall to check ioctl compatness</title>
<updated>2016-03-22T22:36:02+00:00</updated>
<author>
<name>Andy Lutomirski</name>
<email>luto@kernel.org</email>
</author>
<published>2016-03-22T21:25:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a25045ff32dfb4d28c650560d5f2a82c1773dd1c'/>
<id>a25045ff32dfb4d28c650560d5f2a82c1773dd1c</id>
<content type='text'>
Firewire was using is_compat_task to check whether it was in a compat
ioctl or a non-compat ioctl.  Use is_compat_syscall instead so it works
properly on all architectures.

Signed-off-by: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Clemens Ladisch &lt;clemens@ladisch.de&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Firewire was using is_compat_task to check whether it was in a compat
ioctl or a non-compat ioctl.  Use is_compat_syscall instead so it works
properly on all architectures.

Signed-off-by: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Clemens Ladisch &lt;clemens@ladisch.de&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>firewire: nosy: Replace timeval with timespec64</title>
<updated>2016-03-22T14:14:30+00:00</updated>
<author>
<name>Tina Ruchandani</name>
<email>ruchandani.tina@gmail.com</email>
</author>
<published>2016-03-21T05:59:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=384fbb96f9268eee0b703b39cb07557403bd9aac'/>
<id>384fbb96f9268eee0b703b39cb07557403bd9aac</id>
<content type='text'>
'struct timeval' uses a 32 bit field for its 'seconds' value which
will overflow in year 2038 and beyond. This patch replaces the use
of timeval in nosy.c with timespec64 which doesn't suffer from y2038
issue. The code is correct as is - since it is only using the
microseconds portion of timeval. However, this patch does the
replacement as part of a larger effort to remove all instances of
'struct timeval' from the kernel (that would help identify cases
where the code is actually broken).

Signed-off-by: Tina Ruchandani &lt;ruchandani.tina@gmail.com&gt;
Reviewed-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
'struct timeval' uses a 32 bit field for its 'seconds' value which
will overflow in year 2038 and beyond. This patch replaces the use
of timeval in nosy.c with timespec64 which doesn't suffer from y2038
issue. The code is correct as is - since it is only using the
microseconds portion of timeval. However, this patch does the
replacement as part of a larger effort to remove all instances of
'struct timeval' from the kernel (that would help identify cases
where the code is actually broken).

Signed-off-by: Tina Ruchandani &lt;ruchandani.tina@gmail.com&gt;
Reviewed-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'firewire-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394</title>
<updated>2016-03-20T02:21:24+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2016-03-20T02:21:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=1c3d770043583d99118d52cad309f586ef8e7d4a'/>
<id>1c3d770043583d99118d52cad309f586ef8e7d4a</id>
<content type='text'>
Pull firewire updates from Stefan Richter:
 "IEEE 1394 subsystem patches:

   - move away from outmoded timekeeping API
   - error reporting fix
   - documentation bits"

* tag 'firewire-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: ABI documentation: libhinawa uses firewire-cdev
  firewire: ABI documentation: jujuutils were renamed to linux-firewire-utils
  firewire: ohci: propagate return code from soft_reset to probe and resume
  firewire: nosy: Replace timeval with timespec64
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull firewire updates from Stefan Richter:
 "IEEE 1394 subsystem patches:

   - move away from outmoded timekeeping API
   - error reporting fix
   - documentation bits"

* tag 'firewire-updates' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: ABI documentation: libhinawa uses firewire-cdev
  firewire: ABI documentation: jujuutils were renamed to linux-firewire-utils
  firewire: ohci: propagate return code from soft_reset to probe and resume
  firewire: nosy: Replace timeval with timespec64
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'firewire-update' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394</title>
<updated>2015-11-11T18:21:34+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2015-11-11T18:21:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=8d3de01cfa37bfcf54f1d84eafb7db8530b74199'/>
<id>8d3de01cfa37bfcf54f1d84eafb7db8530b74199</id>
<content type='text'>
Pull firewire fix from Stefan Richter:
 "Work around JMicron initialization quirk, which ffected isochronous
  transmission, e.g. audio via FFADO or ALSA"

* tag 'firewire-update' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: ohci: fix JMicron JMB38x IT context discovery
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull firewire fix from Stefan Richter:
 "Work around JMicron initialization quirk, which ffected isochronous
  transmission, e.g. audio via FFADO or ALSA"

* tag 'firewire-update' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: ohci: fix JMicron JMB38x IT context discovery
</pre>
</div>
</content>
</entry>
<entry>
<title>mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd</title>
<updated>2015-11-07T01:50:42+00:00</updated>
<author>
<name>Mel Gorman</name>
<email>mgorman@techsingularity.net</email>
</author>
<published>2015-11-07T00:28:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=d0164adc89f6bb374d304ffcc375c6d2652fe67d'/>
<id>d0164adc89f6bb374d304ffcc375c6d2652fe67d</id>
<content type='text'>
__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.

Signed-off-by: Mel Gorman &lt;mgorman@techsingularity.net&gt;
Acked-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Christoph Lameter &lt;cl@linux.com&gt;
Cc: David Rientjes &lt;rientjes@google.com&gt;
Cc: Vitaly Wool &lt;vitalywool@gmail.com&gt;
Cc: Rik van Riel &lt;riel@redhat.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.

Signed-off-by: Mel Gorman &lt;mgorman@techsingularity.net&gt;
Acked-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Christoph Lameter &lt;cl@linux.com&gt;
Cc: David Rientjes &lt;rientjes@google.com&gt;
Cc: Vitaly Wool &lt;vitalywool@gmail.com&gt;
Cc: Rik van Riel &lt;riel@redhat.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>firewire: ohci: propagate return code from soft_reset to probe and resume</title>
<updated>2015-11-05T13:25:31+00:00</updated>
<author>
<name>Stefan Richter</name>
<email>stefanr@s5r6.in-berlin.de</email>
</author>
<published>2015-11-01T14:52:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a354cf00c71390c46927335fe20b65f38a528b59'/>
<id>a354cf00c71390c46927335fe20b65f38a528b59</id>
<content type='text'>
software_reset() may fail
  - due to unresponsive chip with -EBUSY (-16), or
  - due to ejected or unseated card with -ENODEV (-19).
Let the PCI probe and resume routines log the actual error code instead
of hardwired -EBUSY.

Signed-off-by: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
software_reset() may fail
  - due to unresponsive chip with -EBUSY (-16), or
  - due to ejected or unseated card with -ENODEV (-19).
Let the PCI probe and resume routines log the actual error code instead
of hardwired -EBUSY.

Signed-off-by: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>firewire: nosy: Replace timeval with timespec64</title>
<updated>2015-11-05T13:21:22+00:00</updated>
<author>
<name>Amitoj Kaur Chawla</name>
<email>amitoj1606@gmail.com</email>
</author>
<published>2015-10-21T22:35:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=2ae4b6b20e2004dccf80d804ae52b073377c2f5b'/>
<id>2ae4b6b20e2004dccf80d804ae52b073377c2f5b</id>
<content type='text'>
32 bit systems using 'struct timeval' will break in the year 2038, so
we replace the code appropriately. However, this driver is not broken
in 2038 since we are using only the microseconds portion of the
current time.

This patch replaces timeval with timespec64.

Signed-off-by: Amitoj Kaur Chawla &lt;amitoj1606@gmail.com&gt;
Reviewed-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
32 bit systems using 'struct timeval' will break in the year 2038, so
we replace the code appropriately. However, this driver is not broken
in 2038 since we are using only the microseconds portion of the
current time.

This patch replaces timeval with timespec64.

Signed-off-by: Amitoj Kaur Chawla &lt;amitoj1606@gmail.com&gt;
Reviewed-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>firewire: ohci: fix JMicron JMB38x IT context discovery</title>
<updated>2015-11-05T13:17:30+00:00</updated>
<author>
<name>Stefan Richter</name>
<email>stefanr@s5r6.in-berlin.de</email>
</author>
<published>2015-11-03T00:46:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=100ceb66d5c40cc0c7018e06a9474302470be73c'/>
<id>100ceb66d5c40cc0c7018e06a9474302470be73c</id>
<content type='text'>
Reported by Clifford and Craig for JMicron OHCI-1394 + SDHCI combo
controllers:  Often or even most of the time, the controller is
initialized with the message "added OHCI v1.10 device as card 0, 4 IR +
0 IT contexts, quirks 0x10".  With 0 isochronous transmit DMA contexts
(IT contexts), applications like audio output are impossible.

However, OHCI-1394 demands that at least 4 IT contexts are implemented
by the link layer controller, and indeed JMicron JMB38x do implement
four of them.  Only their IsoXmitIntMask register is unreliable at early
access.

With my own JMB381 single function controller I found:
  - I can reproduce the problem with a lower probability than Craig's.
  - If I put a loop around the section which clears and reads
    IsoXmitIntMask, then either the first or the second attempt will
    return the correct initial mask of 0x0000000f.  I never encountered
    a case of needing more than a second attempt.
  - Consequently, if I put a dummy reg_read(...IsoXmitIntMaskSet)
    before the first write, the subsequent read will return the correct
    result.
  - If I merely ignore a wrong read result and force the known real
    result, later isochronous transmit DMA usage works just fine.

So let's just fix this chip bug up by the latter method.  Tested with
JMB381 on kernel 3.13 and 4.3.

Since OHCI-1394 generally requires 4 IT contexts at a minium, this
workaround is simply applied whenever the initial read of IsoXmitIntMask
returns 0, regardless whether it's a JMicron chip or not.  I never heard
of this issue together with any other chip though.

I am not 100% sure that this fix works on the OHCI-1394 part of JMB380
and JMB388 combo controllers exactly the same as on the JMB381 single-
function controller, but so far I haven't had a chance to let an owner
of a combo chip run a patched kernel.

Strangely enough, IsoRecvIntMask is always reported correctly, even
though it is probed right before IsoXmitIntMask.

Reported-by: Clifford Dunn
Reported-by: Craig Moore &lt;craig.moore@qenos.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
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<pre>
Reported by Clifford and Craig for JMicron OHCI-1394 + SDHCI combo
controllers:  Often or even most of the time, the controller is
initialized with the message "added OHCI v1.10 device as card 0, 4 IR +
0 IT contexts, quirks 0x10".  With 0 isochronous transmit DMA contexts
(IT contexts), applications like audio output are impossible.

However, OHCI-1394 demands that at least 4 IT contexts are implemented
by the link layer controller, and indeed JMicron JMB38x do implement
four of them.  Only their IsoXmitIntMask register is unreliable at early
access.

With my own JMB381 single function controller I found:
  - I can reproduce the problem with a lower probability than Craig's.
  - If I put a loop around the section which clears and reads
    IsoXmitIntMask, then either the first or the second attempt will
    return the correct initial mask of 0x0000000f.  I never encountered
    a case of needing more than a second attempt.
  - Consequently, if I put a dummy reg_read(...IsoXmitIntMaskSet)
    before the first write, the subsequent read will return the correct
    result.
  - If I merely ignore a wrong read result and force the known real
    result, later isochronous transmit DMA usage works just fine.

So let's just fix this chip bug up by the latter method.  Tested with
JMB381 on kernel 3.13 and 4.3.

Since OHCI-1394 generally requires 4 IT contexts at a minium, this
workaround is simply applied whenever the initial read of IsoXmitIntMask
returns 0, regardless whether it's a JMicron chip or not.  I never heard
of this issue together with any other chip though.

I am not 100% sure that this fix works on the OHCI-1394 part of JMB380
and JMB388 combo controllers exactly the same as on the JMB381 single-
function controller, but so far I haven't had a chance to let an owner
of a combo chip run a patched kernel.

Strangely enough, IsoRecvIntMask is always reported correctly, even
though it is probed right before IsoXmitIntMask.

Reported-by: Clifford Dunn
Reported-by: Craig Moore &lt;craig.moore@qenos.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
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