<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/drivers/irqchip, branch v3.12.43</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>irqchip: gic: Fix core ID calculation when topology is read from DT</title>
<updated>2014-07-29T15:01:43+00:00</updated>
<author>
<name>Tomasz Figa</name>
<email>t.figa@samsung.com</email>
</author>
<published>2014-07-17T15:23:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5ef74eaa47bf0fe5e43bbd0d8f0a9d9cb7363a6a'/>
<id>5ef74eaa47bf0fe5e43bbd0d8f0a9d9cb7363a6a</id>
<content type='text'>
commit 29e697b11853d3f83b1864ae385abdad4aa2c361 upstream.

Certain GIC implementation, namely those found on earlier, single
cluster, Exynos SoCs, have registers mapped without per-CPU banking,
which means that the driver needs to use different offset for each CPU.

Currently the driver calculates the offset by multiplying value returned
by cpu_logical_map() by CPU offset parsed from DT. This is correct when
CPU topology is not specified in DT and aforementioned function returns
core ID alone. However when DT contains CPU topology, the function
changes to return cluster ID as well, which is non-zero on mentioned
SoCs and so breaks the calculation in GIC driver.

This patch fixes this by masking out cluster ID in CPU offset
calculation so that only core ID is considered. Multi-cluster Exynos
SoCs already have banked GIC implementations, so this simple fix should
be enough.

Reported-by: Lorenzo Pieralisi &lt;lorenzo.pieralisi@arm.com&gt;
Reported-by: Bartlomiej Zolnierkiewicz &lt;b.zolnierkie@samsung.com&gt;
Signed-off-by: Tomasz Figa &lt;t.figa@samsung.com&gt;
Fixes: db0d4db22a78d ("ARM: gic: allow GIC to support non-banked setups")
Link: https://lkml.kernel.org/r/1405610624-18722-1-git-send-email-t.figa@samsung.com
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 29e697b11853d3f83b1864ae385abdad4aa2c361 upstream.

Certain GIC implementation, namely those found on earlier, single
cluster, Exynos SoCs, have registers mapped without per-CPU banking,
which means that the driver needs to use different offset for each CPU.

Currently the driver calculates the offset by multiplying value returned
by cpu_logical_map() by CPU offset parsed from DT. This is correct when
CPU topology is not specified in DT and aforementioned function returns
core ID alone. However when DT contains CPU topology, the function
changes to return cluster ID as well, which is non-zero on mentioned
SoCs and so breaks the calculation in GIC driver.

This patch fixes this by masking out cluster ID in CPU offset
calculation so that only core ID is considered. Multi-cluster Exynos
SoCs already have banked GIC implementations, so this simple fix should
be enough.

Reported-by: Lorenzo Pieralisi &lt;lorenzo.pieralisi@arm.com&gt;
Reported-by: Bartlomiej Zolnierkiewicz &lt;b.zolnierkie@samsung.com&gt;
Signed-off-by: Tomasz Figa &lt;t.figa@samsung.com&gt;
Fixes: db0d4db22a78d ("ARM: gic: allow GIC to support non-banked setups")
Link: https://lkml.kernel.org/r/1405610624-18722-1-git-send-email-t.figa@samsung.com
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>irqchip: gic: Add support for cortex a7 compatible string</title>
<updated>2014-07-29T15:01:43+00:00</updated>
<author>
<name>Matthias Brugger</name>
<email>matthias.bgg@gmail.com</email>
</author>
<published>2014-07-03T11:58:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=26edd8ddfd1a9fa39fcfe329e39d9675dfe69551'/>
<id>26edd8ddfd1a9fa39fcfe329e39d9675dfe69551</id>
<content type='text'>
commit a97e8027b1d28eafe6bafe062556c1ec926a49c6 upstream.

Patch 0a68214b "ARM: DT: Add binding for GIC virtualization extentions (VGIC)" added
the "arm,cortex-a7-gic" compatible string, but the corresponding IRQCHIP_DECLARE
was never added to the gic driver.

To let real Cortex-A7 SoCs use it, add the necessary declaration to the device driver.

Signed-off-by: Matthias Brugger &lt;matthias.bgg@gmail.com&gt;
Link: https://lkml.kernel.org/r/1404388732-28890-1-git-send-email-matthias.bgg@gmail.com
Fixes: 0a68214b76ca ("ARM: DT: Add binding for GIC virtualization extentions (VGIC)")
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit a97e8027b1d28eafe6bafe062556c1ec926a49c6 upstream.

Patch 0a68214b "ARM: DT: Add binding for GIC virtualization extentions (VGIC)" added
the "arm,cortex-a7-gic" compatible string, but the corresponding IRQCHIP_DECLARE
was never added to the gic driver.

To let real Cortex-A7 SoCs use it, add the necessary declaration to the device driver.

Signed-off-by: Matthias Brugger &lt;matthias.bgg@gmail.com&gt;
Link: https://lkml.kernel.org/r/1404388732-28890-1-git-send-email-matthias.bgg@gmail.com
Fixes: 0a68214b76ca ("ARM: DT: Add binding for GIC virtualization extentions (VGIC)")
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>irqchip: spear_shirq: Fix interrupt offset</title>
<updated>2014-07-18T13:51:08+00:00</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2014-06-19T21:34:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=d90ff081ac4e26e9258a5cb24dc2333d657af0dd'/>
<id>d90ff081ac4e26e9258a5cb24dc2333d657af0dd</id>
<content type='text'>
commit 4f4366033945419b0c52118c29d3057d7c558765 upstream.

The ras3 block on spear320 claims to have 3 interrupts. In fact it has
one and 6 reserved interrupts. Account the 6 reserved to this block so
it has 7 interrupts total. That matches the datasheet and the device
tree entries.

Broken since commit 80515a5a(ARM: SPEAr3xx: shirq: simplify and move
the shared irq multiplexor to DT). Testing is overrated....

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: https://lkml.kernel.org/r/20140619212712.872379208@linutronix.de
Fixes: 80515a5a2e3c ('ARM: SPEAr3xx: shirq: simplify and move the shared irq multiplexor to DT')
Acked-by: Viresh Kumar &lt;viresh.kumar@linaro.org&gt;
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 4f4366033945419b0c52118c29d3057d7c558765 upstream.

The ras3 block on spear320 claims to have 3 interrupts. In fact it has
one and 6 reserved interrupts. Account the 6 reserved to this block so
it has 7 interrupts total. That matches the datasheet and the device
tree entries.

Broken since commit 80515a5a(ARM: SPEAr3xx: shirq: simplify and move
the shared irq multiplexor to DT). Testing is overrated....

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: https://lkml.kernel.org/r/20140619212712.872379208@linutronix.de
Fixes: 80515a5a2e3c ('ARM: SPEAr3xx: shirq: simplify and move the shared irq multiplexor to DT')
Acked-by: Viresh Kumar &lt;viresh.kumar@linaro.org&gt;
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>irqchip: Gic: Support forced affinity setting</title>
<updated>2014-06-06T09:40:20+00:00</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2014-04-16T14:36:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a46aaa63b66b1836ca6ad054003f035d3201548e'/>
<id>a46aaa63b66b1836ca6ad054003f035d3201548e</id>
<content type='text'>
commit ffde1de64012c406dfdda8690918248b472f24e4 upstream.

To support the affinity setting of per cpu timers in the early startup
of a not yet online cpu, implement the force logic, which disables the
cpu online check.

Tagged for stable to allow a simple fix of the affected SoC clock
event drivers.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Tested-by: Krzysztof Kozlowski &lt;k.kozlowski@samsung.com&gt;
Cc: Kyungmin Park &lt;kyungmin.park@samsung.com&gt;
Cc: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: Bartlomiej Zolnierkiewicz &lt;b.zolnierkie@samsung.com&gt;
Cc: Tomasz Figa &lt;t.figa@samsung.com&gt;,
Cc: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;,
Cc: Kukjin Kim &lt;kgene.kim@samsung.com&gt;
Cc: linux-arm-kernel@lists.infradead.org,
Link: http://lkml.kernel.org/r/20140416143315.916984416@linutronix.de
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit ffde1de64012c406dfdda8690918248b472f24e4 upstream.

To support the affinity setting of per cpu timers in the early startup
of a not yet online cpu, implement the force logic, which disables the
cpu online check.

Tagged for stable to allow a simple fix of the affected SoC clock
event drivers.

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Tested-by: Krzysztof Kozlowski &lt;k.kozlowski@samsung.com&gt;
Cc: Kyungmin Park &lt;kyungmin.park@samsung.com&gt;
Cc: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: Bartlomiej Zolnierkiewicz &lt;b.zolnierkie@samsung.com&gt;
Cc: Tomasz Figa &lt;t.figa@samsung.com&gt;,
Cc: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;,
Cc: Kukjin Kim &lt;kgene.kim@samsung.com&gt;
Cc: linux-arm-kernel@lists.infradead.org,
Link: http://lkml.kernel.org/r/20140416143315.916984416@linutronix.de
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>irq-metag*: stop set_affinity vectoring to offline cpus</title>
<updated>2014-03-05T16:13:54+00:00</updated>
<author>
<name>James Hogan</name>
<email>james.hogan@imgtec.com</email>
</author>
<published>2014-02-25T22:05:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=23c0ac16e67d6583d4ca1fa1e1bbf4e66d019bb2'/>
<id>23c0ac16e67d6583d4ca1fa1e1bbf4e66d019bb2</id>
<content type='text'>
commit f229006ec6beabf7b844653d92fa61f025fe3dcf upstream.

Fix irq_set_affinity callbacks in the Meta IRQ chip drivers to AND
cpu_online_mask into the cpumask when picking a CPU to vector the
interrupt to.

As Thomas pointed out, the /proc/irq/$N/smp_affinity interface doesn't
filter out offline CPUs, so without this patch if you offline CPU0 and
set an IRQ affinity to 0x3 it vectors the interrupt onto CPU0 even
though it is offline.

Reported-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: James Hogan &lt;james.hogan@imgtec.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: linux-metag@vger.kernel.org
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit f229006ec6beabf7b844653d92fa61f025fe3dcf upstream.

Fix irq_set_affinity callbacks in the Meta IRQ chip drivers to AND
cpu_online_mask into the cpumask when picking a CPU to vector the
interrupt to.

As Thomas pointed out, the /proc/irq/$N/smp_affinity interface doesn't
filter out offline CPUs, so without this patch if you offline CPU0 and
set an IRQ affinity to 0x3 it vectors the interrupt onto CPU0 even
though it is offline.

Reported-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: James Hogan &lt;james.hogan@imgtec.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: linux-metag@vger.kernel.org
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>irqchip: orion: Fix getting generic chip pointer.</title>
<updated>2014-03-05T16:13:52+00:00</updated>
<author>
<name>Andrew Lunn</name>
<email>andrew@lunn.ch</email>
</author>
<published>2014-02-06T23:41:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=054865c954ae9d31e5cfd1010e6e15a02d39ce96'/>
<id>054865c954ae9d31e5cfd1010e6e15a02d39ce96</id>
<content type='text'>
commit d86e9af6336c0ad586a5dbd70064253d40bbb5ff upstream.

Enabling SPARSE_IRQ shows up a bug in the irq-orion bridge interrupt
handler. The bridge interrupt is implemented using a single generic
chip. Thus the parameter passed to irq_get_domain_generic_chip()
should always be zero.

Signed-off-by: Andrew Lunn &lt;andrew@lunn.ch&gt;
Acked-by: Sebastian Hesselbarth &lt;sebastian.hesselbarth@gmail.com&gt;
Fixes: 9dbd90f17e4f ("irqchip: Add support for Marvell Orion SoCs")
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit d86e9af6336c0ad586a5dbd70064253d40bbb5ff upstream.

Enabling SPARSE_IRQ shows up a bug in the irq-orion bridge interrupt
handler. The bridge interrupt is implemented using a single generic
chip. Thus the parameter passed to irq_get_domain_generic_chip()
should always be zero.

Signed-off-by: Andrew Lunn &lt;andrew@lunn.ch&gt;
Acked-by: Sebastian Hesselbarth &lt;sebastian.hesselbarth@gmail.com&gt;
Fixes: 9dbd90f17e4f ("irqchip: Add support for Marvell Orion SoCs")
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>irqchip: orion: clear stale interrupts in irq_startup</title>
<updated>2014-03-05T16:13:52+00:00</updated>
<author>
<name>Sebastian Hesselbarth</name>
<email>sebastian.hesselbarth@gmail.com</email>
</author>
<published>2014-01-23T23:10:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=6b32598699db3b8f60ed3d2ffa50b880c95e1fd5'/>
<id>6b32598699db3b8f60ed3d2ffa50b880c95e1fd5</id>
<content type='text'>
commit e0318ec3bf3f1502cd11b21b1eb00aa355b40b67 upstream.

Bridge IRQ_CAUSE bits are asserted regardless of the corresponding bit in
IRQ_MASK register. To avoid interrupt events on stale irqs, we have to clear
them before unmask. This installs an .irq_startup callback to ensure stale
irqs are cleared before initial unmask.

Signed-off-by: Sebastian Hesselbarth &lt;sebastian.hesselbarth@gmail.com&gt;
Tested-by: Ezequiel Garcia &lt;ezequiel.garcia@free-electrons.com&gt;
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit e0318ec3bf3f1502cd11b21b1eb00aa355b40b67 upstream.

Bridge IRQ_CAUSE bits are asserted regardless of the corresponding bit in
IRQ_MASK register. To avoid interrupt events on stale irqs, we have to clear
them before unmask. This installs an .irq_startup callback to ensure stale
irqs are cleared before initial unmask.

Signed-off-by: Sebastian Hesselbarth &lt;sebastian.hesselbarth@gmail.com&gt;
Tested-by: Ezequiel Garcia &lt;ezequiel.garcia@free-electrons.com&gt;
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>irqchip: orion: use handle_edge_irq on bridge irqs</title>
<updated>2014-03-05T16:13:52+00:00</updated>
<author>
<name>Sebastian Hesselbarth</name>
<email>sebastian.hesselbarth@gmail.com</email>
</author>
<published>2014-01-23T22:38:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=f702de8127e146a0d21be1bd532959c9ef9f4977'/>
<id>f702de8127e146a0d21be1bd532959c9ef9f4977</id>
<content type='text'>
commit 5f40067fc86f0e49329ad4a852c278998ff4394e upstream.

Bridge irqs are edge-triggered, i.e. they get asserted on low-to-high
transitions and not on the level of the downstream interrupt line.
This replaces handle_level_irq by the more appropriate handle_edge_irq.

Signed-off-by: Sebastian Hesselbarth &lt;sebastian.hesselbarth@gmail.com&gt;
Tested-by: Ezequiel Garcia &lt;ezequiel.garcia@free-electrons.com&gt;
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 5f40067fc86f0e49329ad4a852c278998ff4394e upstream.

Bridge irqs are edge-triggered, i.e. they get asserted on low-to-high
transitions and not on the level of the downstream interrupt line.
This replaces handle_level_irq by the more appropriate handle_edge_irq.

Signed-off-by: Sebastian Hesselbarth &lt;sebastian.hesselbarth@gmail.com&gt;
Tested-by: Ezequiel Garcia &lt;ezequiel.garcia@free-electrons.com&gt;
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>irqchip: orion: clear bridge cause register on init</title>
<updated>2014-03-05T16:13:52+00:00</updated>
<author>
<name>Sebastian Hesselbarth</name>
<email>sebastian.hesselbarth@gmail.com</email>
</author>
<published>2014-01-23T22:38:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=dd14a330306a608820bb7eb4983443e6145483c7'/>
<id>dd14a330306a608820bb7eb4983443e6145483c7</id>
<content type='text'>
commit 7b119fd1bdc59a8060df5b659b9f7a70e0169fd6 upstream.

It is good practice to mask and clear pending irqs on init. We already
mask all irqs, so also clear the bridge irq cause register.

Signed-off-by: Sebastian Hesselbarth &lt;sebastian.hesselbarth@gmail.com&gt;
Tested-by: Ezequiel Garcia &lt;ezequiel.garcia@free-electrons.com&gt;
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 7b119fd1bdc59a8060df5b659b9f7a70e0169fd6 upstream.

It is good practice to mask and clear pending irqs on init. We already
mask all irqs, so also clear the bridge irq cause register.

Signed-off-by: Sebastian Hesselbarth &lt;sebastian.hesselbarth@gmail.com&gt;
Tested-by: Ezequiel Garcia &lt;ezequiel.garcia@free-electrons.com&gt;
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>irqchip: armada-370-xp: fix IPI race condition</title>
<updated>2014-02-20T19:07:59+00:00</updated>
<author>
<name>Lior Amsalem</name>
<email>alior@marvell.com</email>
</author>
<published>2013-11-25T16:26:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=97ec8cd5d1535e8a6f09bf029a8013a33e32ed38'/>
<id>97ec8cd5d1535e8a6f09bf029a8013a33e32ed38</id>
<content type='text'>
commit a6f089e95b1e08cdea9633d50ad20aa5d44ba64d upstream.

In the Armada 370/XP driver, when we receive an IRQ 0, we read the
list of doorbells that caused the interrupt from register
ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS. This gives the list of IPIs that
were generated. However, instead of acknowledging only the IPIs that
were generated, we acknowledge *all* the IPIs, by writing
~IPI_DOORBELL_MASK in the ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS register.

This creates a race condition: if a new IPI that isn't part of the
ones read into the temporary "ipimask" variable is fired before we
acknowledge all IPIs, then we will simply loose it. This is causing
scheduling hangs on SMP intensive workloads.

It is important to mention that this ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS
register has the following behavior: "A CPU write of 0 clears the bits
in this field. A CPU write of 1 has no effect". This is what allows us
to simply write ~ipimask to acknoledge the handled IPIs.

Notice that the same problem is present in the MSI implementation, but
it will be fixed as a separate patch, so that this IPI fix can be
pushed to older stable versions as appropriate (all the way to 3.8),
while the MSI code only appeared in 3.13.

Signed-off-by: Lior Amsalem &lt;alior@marvell.com&gt;
Signed-off-by: Thomas Petazzoni &lt;thomas.petazzoni@free-electrons.com&gt;
Fixes: 344e873e5657e8dc0 'arm: mvebu: Add IPI support via doorbells'
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

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<pre>
commit a6f089e95b1e08cdea9633d50ad20aa5d44ba64d upstream.

In the Armada 370/XP driver, when we receive an IRQ 0, we read the
list of doorbells that caused the interrupt from register
ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS. This gives the list of IPIs that
were generated. However, instead of acknowledging only the IPIs that
were generated, we acknowledge *all* the IPIs, by writing
~IPI_DOORBELL_MASK in the ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS register.

This creates a race condition: if a new IPI that isn't part of the
ones read into the temporary "ipimask" variable is fired before we
acknowledge all IPIs, then we will simply loose it. This is causing
scheduling hangs on SMP intensive workloads.

It is important to mention that this ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS
register has the following behavior: "A CPU write of 0 clears the bits
in this field. A CPU write of 1 has no effect". This is what allows us
to simply write ~ipimask to acknoledge the handled IPIs.

Notice that the same problem is present in the MSI implementation, but
it will be fixed as a separate patch, so that this IPI fix can be
pushed to older stable versions as appropriate (all the way to 3.8),
while the MSI code only appeared in 3.13.

Signed-off-by: Lior Amsalem &lt;alior@marvell.com&gt;
Signed-off-by: Thomas Petazzoni &lt;thomas.petazzoni@free-electrons.com&gt;
Fixes: 344e873e5657e8dc0 'arm: mvebu: Add IPI support via doorbells'
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Jason Cooper &lt;jason@lakedaemon.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
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