Hi,
I need one help.
I am using i.MX7 Sabre board with kernel version 4.1.15
Let's say I am interested in GPIO number: 21
I wanted to set CPU affinity for particular GPIO->IRQ number, so I
tried the below steps:
root@10:~# echo 21 > /sys/class/gpio/export
root@10:~# echo "rising" > /sys/class/gpio/gpio21/edge
root@10:~# cat /proc/interrupts | grep 21
47: 0 0 gpio-mxc 21 Edge gpiolib
root@10:~# cat /sys/class/gpio/gpio21/direction
in
root@10:~# cat /proc/irq/47/smp_affinity
3
root@10:~# echo 2 > /proc/irq/47/smp_affinity
-bash: echo: write error: Input/output error
But I get input/output error.
When I debug further, found that irq_can_set_affinity is returning 0:
[ 0.000000] genirq: irq_can_set_affinity (0): balance: 1,
irq_data.chip: a81b7e48, irq_set_affinity: (null)
[ 0.000000] write_irq_affinity: FAIL
I also tried first setting /proc/irq/default_smp_affinity to 2 (from 3).
This change is working, but the smp_affinity setting for the new IRQ
is not working.
When I try to set smp_affinity for mmc0, then it works.
# cat /proc/interrupts | grep mmc
295: 55 0 GPCV2 22 Edge mmc0
296: 0 0 GPCV2 23 Edge mmc1
297: 52 0 GPCV2 24 Edge mmc2
root@10:~# echo 2 > /proc/irq/295/smp_affinity
root@10:~#
So, I wanted to know what are the conditions for which setting
smp_affinity for an IRQ will work ?
Is there any way by which I can set CPU affinity to a GPIO -> IRQ ?
Whether, irq_set_affinity_hint() will work in this case ?
Thanks,
Pintu
On Fri, May 11, 2018 at 05:07:37PM +0530, Pintu Kumar wrote:
> Hi,
>
> I need one help.
> I am using i.MX7 Sabre board with kernel version 4.1.15
>
> Let's say I am interested in GPIO number: 21
> I wanted to set CPU affinity for particular GPIO->IRQ number, so I
> tried the below steps:
> root@10:~# echo 21 > /sys/class/gpio/export
> root@10:~# echo "rising" > /sys/class/gpio/gpio21/edge
> root@10:~# cat /proc/interrupts | grep 21
> 47: 0 0 gpio-mxc 21 Edge gpiolib
> root@10:~# cat /sys/class/gpio/gpio21/direction
> in
> root@10:~# cat /proc/irq/47/smp_affinity
> 3
> root@10:~# echo 2 > /proc/irq/47/smp_affinity
> -bash: echo: write error: Input/output error
>
> But I get input/output error.
> When I debug further, found that irq_can_set_affinity is returning 0:
> [ 0.000000] genirq: irq_can_set_affinity (0): balance: 1,
> irq_data.chip: a81b7e48, irq_set_affinity: (null)
> [ 0.000000] write_irq_affinity: FAIL
>
> I also tried first setting /proc/irq/default_smp_affinity to 2 (from 3).
> This change is working, but the smp_affinity setting for the new IRQ
> is not working.
>
> When I try to set smp_affinity for mmc0, then it works.
> # cat /proc/interrupts | grep mmc
> 295: 55 0 GPCV2 22 Edge mmc0
> 296: 0 0 GPCV2 23 Edge mmc1
> 297: 52 0 GPCV2 24 Edge mmc2
>
> root@10:~# echo 2 > /proc/irq/295/smp_affinity
> root@10:~#
>
>
> So, I wanted to know what are the conditions for which setting
> smp_affinity for an IRQ will work ?
>
> Is there any way by which I can set CPU affinity to a GPIO -> IRQ ?
> Whether, irq_set_affinity_hint() will work in this case ?
IRQ affinity is only supported where interrupts are _directly_ wired to
the GIC. It's the GIC which does the interrupt steering to the CPU
cores.
Interrupts on downstream interrupt controllers (such as GPCV2) have no
ability to be directed independently to other CPUs - the only possible
way to change the mapping is to move _all_ interrupts on that controller,
and any downstream chained interrupts at GIC level.
Hence why Interrupt 295 has no irq_set_affinity function: there is no way
for the interrupt controller itself to change the affinity of the input
interrupt.
--
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Am Freitag, den 11.05.2018, 13:39 +0100 schrieb Russell King - ARM Linux:
> On Fri, May 11, 2018 at 05:07:37PM +0530, Pintu Kumar wrote:
> > Hi,
> >
> > I need one help.
> > I am using i.MX7 Sabre board with kernel version 4.1.15
> >
> > Let's say I am interested in GPIO number: 21
> > I wanted to set CPU affinity for particular GPIO->IRQ number, so I
> > tried the below steps:
> > root@10:~# echo 21 > /sys/class/gpio/export
> > root@10:~# echo "rising" > /sys/class/gpio/gpio21/edge
> > root@10:~# cat /proc/interrupts | grep 21
> > 47: 0 0 gpio-mxc 21 Edge gpiolib
> > root@10:~# cat /sys/class/gpio/gpio21/direction
> > in
> > root@10:~# cat /proc/irq/47/smp_affinity
> > 3
> > root@10:~# echo 2 > /proc/irq/47/smp_affinity
> > -bash: echo: write error: Input/output error
> >
> > But I get input/output error.
> > When I debug further, found that irq_can_set_affinity is returning 0:
> > [ 0.000000] genirq: irq_can_set_affinity (0): balance: 1,
> > irq_data.chip: a81b7e48, irq_set_affinity: (null)
> > [ 0.000000] write_irq_affinity: FAIL
> >
> > I also tried first setting /proc/irq/default_smp_affinity to 2 (from 3).
> > This change is working, but the smp_affinity setting for the new IRQ
> > is not working.
> >
> > When I try to set smp_affinity for mmc0, then it works.
> > # cat /proc/interrupts | grep mmc
> > 295: 55 0 GPCV2 22 Edge mmc0
> > 296: 0 0 GPCV2 23 Edge mmc1
> > 297: 52 0 GPCV2 24 Edge mmc2
> >
> > root@10:~# echo 2 > /proc/irq/295/smp_affinity
> > root@10:~#
> >
> >
> > So, I wanted to know what are the conditions for which setting
> > smp_affinity for an IRQ will work ?
> >
> > Is there any way by which I can set CPU affinity to a GPIO -> IRQ ?
> > Whether, irq_set_affinity_hint() will work in this case ?
>
> IRQ affinity is only supported where interrupts are _directly_ wired to
> the GIC. It's the GIC which does the interrupt steering to the CPU
> cores.
>
> Interrupts on downstream interrupt controllers (such as GPCV2) have no
> ability to be directed independently to other CPUs - the only possible
> way to change the mapping is to move _all_ interrupts on that controller,
> and any downstream chained interrupts at GIC level.
>
> Hence why Interrupt 295 has no irq_set_affinity function: there is no way
> for the interrupt controller itself to change the affinity of the input
> interrupt.
The GPCv2 though is a secondary IRQ controller which has a 1:1 mapping
of its input IRQs to the upstream GIC IRQ lines. Affinity can thus be
handled by forwarding the request to the GIC by
irq_chip_set_affinity_parent().
As this is handled correctly in the upstream kernel since the first
commit introducing support for the GPCv2, it seems the issue is only
present in some downstream kernel.
Regards,
Lucas
On Fri, May 11, 2018 at 6:34 PM, Lucas Stach <[email protected]> wrote:
> Am Freitag, den 11.05.2018, 13:39 +0100 schrieb Russell King - ARM Linux:
>> On Fri, May 11, 2018 at 05:07:37PM +0530, Pintu Kumar wrote:
>> > Hi,
>> >
>> > I need one help.
>> > I am using i.MX7 Sabre board with kernel version 4.1.15
>> >
>> > Let's say I am interested in GPIO number: 21
>> > I wanted to set CPU affinity for particular GPIO->IRQ number, so I
>> > tried the below steps:
>> > root@10:~# echo 21 > /sys/class/gpio/export
>> > root@10:~# echo "rising" > /sys/class/gpio/gpio21/edge
>> > root@10:~# cat /proc/interrupts | grep 21
>> > 47: 0 0 gpio-mxc 21 Edge gpiolib
>> > root@10:~# cat /sys/class/gpio/gpio21/direction
>> > in
>> > root@10:~# cat /proc/irq/47/smp_affinity
>> > 3
>> > root@10:~# echo 2 > /proc/irq/47/smp_affinity
>> > -bash: echo: write error: Input/output error
>> >
>> > But I get input/output error.
>> > When I debug further, found that irq_can_set_affinity is returning 0:
>> > [ 0.000000] genirq: irq_can_set_affinity (0): balance: 1,
>> > irq_data.chip: a81b7e48, irq_set_affinity: (null)
>> > [ 0.000000] write_irq_affinity: FAIL
>> >
>> > I also tried first setting /proc/irq/default_smp_affinity to 2 (from 3).
>> > This change is working, but the smp_affinity setting for the new IRQ
>> > is not working.
>> >
>> > When I try to set smp_affinity for mmc0, then it works.
>> > # cat /proc/interrupts | grep mmc
>> > 295: 55 0 GPCV2 22 Edge mmc0
>> > 296: 0 0 GPCV2 23 Edge mmc1
>> > 297: 52 0 GPCV2 24 Edge mmc2
>> >
>> > root@10:~# echo 2 > /proc/irq/295/smp_affinity
>> > root@10:~#
>> >
>> >
>> > So, I wanted to know what are the conditions for which setting
>> > smp_affinity for an IRQ will work ?
>> >
>> > Is there any way by which I can set CPU affinity to a GPIO -> IRQ ?
>> > Whether, irq_set_affinity_hint() will work in this case ?
>>
>> IRQ affinity is only supported where interrupts are _directly_ wired to
>> the GIC. It's the GIC which does the interrupt steering to the CPU
>> cores.
>>
>> Interrupts on downstream interrupt controllers (such as GPCV2) have no
>> ability to be directed independently to other CPUs - the only possible
>> way to change the mapping is to move _all_ interrupts on that controller,
>> and any downstream chained interrupts at GIC level.
>>
>> Hence why Interrupt 295 has no irq_set_affinity function: there is no way
>> for the interrupt controller itself to change the affinity of the input
>> interrupt.
>
> The GPCv2 though is a secondary IRQ controller which has a 1:1 mapping
> of its input IRQs to the upstream GIC IRQ lines. Affinity can thus be
> handled by forwarding the request to the GIC by
> irq_chip_set_affinity_parent().
>
> As this is handled correctly in the upstream kernel since the first
> commit introducing support for the GPCv2, it seems the issue is only
> present in some downstream kernel.
>
OK. Thanks so much for your reply.
I saw some of the drivers using irq_set_affinity_hint() to force the
IRQ affinity to a particular CPU.
This is the sample:
{
cpumask_clear(mask);
cpumask_set_cpu(cpu, mask);
irq_set_affinity_hint(irq, mask);
}
Whether this logic will work for a particular GPIO pin ?
> Regards,
> Lucas
Hi,
Is there any work around possible to set IRQ affinity for some GPIO interrupt ?
How to avoid CPU0 to receive the current GPIO interrupt ?
How do we assign GPIO interrupts to any CPU other than CPU0 ?
Is it possible to isolate CPU0 for a sometime, from my GPIO driver so
that GPIO interrupt can be served by another CPU ?
Need your inputs to decide whether it is still possible to set
affinity for GPIO interrupt, or its impossible ?
Thanks,
Pintu
On Fri, May 11, 2018 at 8:07 PM, Pintu Kumar <[email protected]> wrote:
> On Fri, May 11, 2018 at 6:34 PM, Lucas Stach <[email protected]> wrote:
>> Am Freitag, den 11.05.2018, 13:39 +0100 schrieb Russell King - ARM Linux:
>>> On Fri, May 11, 2018 at 05:07:37PM +0530, Pintu Kumar wrote:
>>> > Hi,
>>> >
>>> > I need one help.
>>> > I am using i.MX7 Sabre board with kernel version 4.1.15
>>> >
>>> > Let's say I am interested in GPIO number: 21
>>> > I wanted to set CPU affinity for particular GPIO->IRQ number, so I
>>> > tried the below steps:
>>> > root@10:~# echo 21 > /sys/class/gpio/export
>>> > root@10:~# echo "rising" > /sys/class/gpio/gpio21/edge
>>> > root@10:~# cat /proc/interrupts | grep 21
>>> > 47: 0 0 gpio-mxc 21 Edge gpiolib
>>> > root@10:~# cat /sys/class/gpio/gpio21/direction
>>> > in
>>> > root@10:~# cat /proc/irq/47/smp_affinity
>>> > 3
>>> > root@10:~# echo 2 > /proc/irq/47/smp_affinity
>>> > -bash: echo: write error: Input/output error
>>> >
>>> > But I get input/output error.
>>> > When I debug further, found that irq_can_set_affinity is returning 0:
>>> > [ 0.000000] genirq: irq_can_set_affinity (0): balance: 1,
>>> > irq_data.chip: a81b7e48, irq_set_affinity: (null)
>>> > [ 0.000000] write_irq_affinity: FAIL
>>> >
>>> > I also tried first setting /proc/irq/default_smp_affinity to 2 (from 3).
>>> > This change is working, but the smp_affinity setting for the new IRQ
>>> > is not working.
>>> >
>>> > When I try to set smp_affinity for mmc0, then it works.
>>> > # cat /proc/interrupts | grep mmc
>>> > 295: 55 0 GPCV2 22 Edge mmc0
>>> > 296: 0 0 GPCV2 23 Edge mmc1
>>> > 297: 52 0 GPCV2 24 Edge mmc2
>>> >
>>> > root@10:~# echo 2 > /proc/irq/295/smp_affinity
>>> > root@10:~#
>>> >
>>> >
>>> > So, I wanted to know what are the conditions for which setting
>>> > smp_affinity for an IRQ will work ?
>>> >
>>> > Is there any way by which I can set CPU affinity to a GPIO -> IRQ ?
>>> > Whether, irq_set_affinity_hint() will work in this case ?
>>>
>>> IRQ affinity is only supported where interrupts are _directly_ wired to
>>> the GIC. It's the GIC which does the interrupt steering to the CPU
>>> cores.
>>>
>>> Interrupts on downstream interrupt controllers (such as GPCV2) have no
>>> ability to be directed independently to other CPUs - the only possible
>>> way to change the mapping is to move _all_ interrupts on that controller,
>>> and any downstream chained interrupts at GIC level.
>>>
>>> Hence why Interrupt 295 has no irq_set_affinity function: there is no way
>>> for the interrupt controller itself to change the affinity of the input
>>> interrupt.
>>
>> The GPCv2 though is a secondary IRQ controller which has a 1:1 mapping
>> of its input IRQs to the upstream GIC IRQ lines. Affinity can thus be
>> handled by forwarding the request to the GIC by
>> irq_chip_set_affinity_parent().
>>
>> As this is handled correctly in the upstream kernel since the first
>> commit introducing support for the GPCv2, it seems the issue is only
>> present in some downstream kernel.
>>
>
> OK. Thanks so much for your reply.
>
> I saw some of the drivers using irq_set_affinity_hint() to force the
> IRQ affinity to a particular CPU.
> This is the sample:
> {
> cpumask_clear(mask);
> cpumask_set_cpu(cpu, mask);
> irq_set_affinity_hint(irq, mask);
> }
>
> Whether this logic will work for a particular GPIO pin ?
>
>
>> Regards,
>> Lucas
Am Montag, den 14.05.2018, 17:42 +0530 schrieb Pintu Kumar:
> Hi,
>
> Is there any work around possible to set IRQ affinity for some GPIO
> interrupt ?
> How to avoid CPU0 to receive the current GPIO interrupt ?
> How do we assign GPIO interrupts to any CPU other than CPU0 ?
> Is it possible to isolate CPU0 for a sometime, from my GPIO driver so
> that GPIO interrupt can be served by another CPU ?
>
> Need your inputs to decide whether it is still possible to set
> affinity for GPIO interrupt, or its impossible ?
This is not possible. The GPIO IRQs are aggregated into one GPC/GIC IRQ
line per GPIO bank, so it is not possible to change affinity of a
single GPIO interrupt to another CPU. Best we could do is change the
affinity of the whole bank, but given the limited usefulness of
something like that, nobody bothered to implement such a thing.
Regards,
Lucas
>
>
> On Fri, May 11, 2018 at 8:07 PM, Pintu Kumar <[email protected]>
> wrote:
> > On Fri, May 11, 2018 at 6:34 PM, Lucas Stach <[email protected]
> > e> wrote:
> > > Am Freitag, den 11.05.2018, 13:39 +0100 schrieb Russell King -
> > > ARM Linux:
> > > > On Fri, May 11, 2018 at 05:07:37PM +0530, Pintu Kumar wrote:
> > > > > Hi,
> > > > >
> > > > > I need one help.
> > > > > I am using i.MX7 Sabre board with kernel version 4.1.15
> > > > >
> > > > > Let's say I am interested in GPIO number: 21
> > > > > I wanted to set CPU affinity for particular GPIO->IRQ number,
> > > > > so I
> > > > > tried the below steps:
> > > > > root@10:~# echo 21 > /sys/class/gpio/export
> > > > > root@10:~# echo "rising" > /sys/class/gpio/gpio21/edge
> > > > > root@10:~# cat /proc/interrupts | grep 21
> > > > > 47: 0 0 gpio-mxc 21 Edge gpiolib
> > > > > root@10:~# cat /sys/class/gpio/gpio21/direction
> > > > > in
> > > > > root@10:~# cat /proc/irq/47/smp_affinity
> > > > > 3
> > > > > root@10:~# echo 2 > /proc/irq/47/smp_affinity
> > > > > -bash: echo: write error: Input/output error
> > > > >
> > > > > But I get input/output error.
> > > > > When I debug further, found that irq_can_set_affinity is
> > > > > returning 0:
> > > > > [ 0.000000] genirq: irq_can_set_affinity (0): balance: 1,
> > > > > irq_data.chip: a81b7e48, irq_set_affinity: (null)
> > > > > [ 0.000000] write_irq_affinity: FAIL
> > > > >
> > > > > I also tried first setting /proc/irq/default_smp_affinity to
> > > > > 2 (from 3).
> > > > > This change is working, but the smp_affinity setting for the
> > > > > new IRQ
> > > > > is not working.
> > > > >
> > > > > When I try to set smp_affinity for mmc0, then it works.
> > > > > # cat /proc/interrupts | grep mmc
> > > > > 295: 55 0 GPCV2 22 Edge mmc0
> > > > > 296: 0 0 GPCV2 23 Edge mmc1
> > > > > 297: 52 0 GPCV2 24 Edge mmc2
> > > > >
> > > > > root@10:~# echo 2 > /proc/irq/295/smp_affinity
> > > > > root@10:~#
> > > > >
> > > > >
> > > > > So, I wanted to know what are the conditions for which
> > > > > setting
> > > > > smp_affinity for an IRQ will work ?
> > > > >
> > > > > Is there any way by which I can set CPU affinity to a GPIO ->
> > > > > IRQ ?
> > > > > Whether, irq_set_affinity_hint() will work in this case ?
> > > >
> > > > IRQ affinity is only supported where interrupts are _directly_
> > > > wired to
> > > > the GIC. It's the GIC which does the interrupt steering to the
> > > > CPU
> > > > cores.
> > > >
> > > > Interrupts on downstream interrupt controllers (such as GPCV2)
> > > > have no
> > > > ability to be directed independently to other CPUs - the only
> > > > possible
> > > > way to change the mapping is to move _all_ interrupts on that
> > > > controller,
> > > > and any downstream chained interrupts at GIC level.
> > > >
> > > > Hence why Interrupt 295 has no irq_set_affinity function: there
> > > > is no way
> > > > for the interrupt controller itself to change the affinity of
> > > > the input
> > > > interrupt.
> > >
> > > The GPCv2 though is a secondary IRQ controller which has a 1:1
> > > mapping
> > > of its input IRQs to the upstream GIC IRQ lines. Affinity can
> > > thus be
> > > handled by forwarding the request to the GIC by
> > > irq_chip_set_affinity_parent().
> > >
> > > As this is handled correctly in the upstream kernel since the
> > > first
> > > commit introducing support for the GPCv2, it seems the issue is
> > > only
> > > present in some downstream kernel.
> > >
> >
> > OK. Thanks so much for your reply.
> >
> > I saw some of the drivers using irq_set_affinity_hint() to force
> > the
> > IRQ affinity to a particular CPU.
> > This is the sample:
> > {
> > cpumask_clear(mask);
> > cpumask_set_cpu(cpu, mask);
> > irq_set_affinity_hint(irq, mask);
> > }
> >
> > Whether this logic will work for a particular GPIO pin ?
> >
> >
> > > Regards,
> > > Lucas
On Mon, May 14, 2018 at 6:41 PM, Lucas Stach <[email protected]> wrote:
> Am Montag, den 14.05.2018, 17:42 +0530 schrieb Pintu Kumar:
>> Hi,
>>
>> Is there any work around possible to set IRQ affinity for some GPIO
>> interrupt ?
>> How to avoid CPU0 to receive the current GPIO interrupt ?
>> How do we assign GPIO interrupts to any CPU other than CPU0 ?
>> Is it possible to isolate CPU0 for a sometime, from my GPIO driver so
>> that GPIO interrupt can be served by another CPU ?
>>
>> Need your inputs to decide whether it is still possible to set
>> affinity for GPIO interrupt, or its impossible ?
>
> This is not possible. The GPIO IRQs are aggregated into one GPC/GIC IRQ
> line per GPIO bank, so it is not possible to change affinity of a
> single GPIO interrupt to another CPU.
OK. Thanks for your confirmation.
> Best we could do is change the
> affinity of the whole bank,
OK. How can we do this on the fly from my driver code.
If you have any reference please let me know.
This is required only for experimental purpose to prove the point to be mgmt.
My idea is, from the driver, change the affinity of the whole bank.
So, the GPIO interrupt can be delivered on to this specific CPU bank.
Once I am done, I will revert back to the old bank.
Please give me some hint on how to do this from my kernel module....
> but given the limited usefulness of
> something like that, nobody bothered to implement such a thing.
>
> Regards,
> Lucas
>
>>
>>
>> On Fri, May 11, 2018 at 8:07 PM, Pintu Kumar <[email protected]>
>> wrote:
>> > On Fri, May 11, 2018 at 6:34 PM, Lucas Stach <[email protected]
>> > e> wrote:
>> > > Am Freitag, den 11.05.2018, 13:39 +0100 schrieb Russell King -
>> > > ARM Linux:
>> > > > On Fri, May 11, 2018 at 05:07:37PM +0530, Pintu Kumar wrote:
>> > > > > Hi,
>> > > > >
>> > > > > I need one help.
>> > > > > I am using i.MX7 Sabre board with kernel version 4.1.15
>> > > > >
>> > > > > Let's say I am interested in GPIO number: 21
>> > > > > I wanted to set CPU affinity for particular GPIO->IRQ number,
>> > > > > so I
>> > > > > tried the below steps:
>> > > > > root@10:~# echo 21 > /sys/class/gpio/export
>> > > > > root@10:~# echo "rising" > /sys/class/gpio/gpio21/edge
>> > > > > root@10:~# cat /proc/interrupts | grep 21
>> > > > > 47: 0 0 gpio-mxc 21 Edge gpiolib
>> > > > > root@10:~# cat /sys/class/gpio/gpio21/direction
>> > > > > in
>> > > > > root@10:~# cat /proc/irq/47/smp_affinity
>> > > > > 3
>> > > > > root@10:~# echo 2 > /proc/irq/47/smp_affinity
>> > > > > -bash: echo: write error: Input/output error
>> > > > >
>> > > > > But I get input/output error.
>> > > > > When I debug further, found that irq_can_set_affinity is
>> > > > > returning 0:
>> > > > > [ 0.000000] genirq: irq_can_set_affinity (0): balance: 1,
>> > > > > irq_data.chip: a81b7e48, irq_set_affinity: (null)
>> > > > > [ 0.000000] write_irq_affinity: FAIL
>> > > > >
>> > > > > I also tried first setting /proc/irq/default_smp_affinity to
>> > > > > 2 (from 3).
>> > > > > This change is working, but the smp_affinity setting for the
>> > > > > new IRQ
>> > > > > is not working.
>> > > > >
>> > > > > When I try to set smp_affinity for mmc0, then it works.
>> > > > > # cat /proc/interrupts | grep mmc
>> > > > > 295: 55 0 GPCV2 22 Edge mmc0
>> > > > > 296: 0 0 GPCV2 23 Edge mmc1
>> > > > > 297: 52 0 GPCV2 24 Edge mmc2
>> > > > >
>> > > > > root@10:~# echo 2 > /proc/irq/295/smp_affinity
>> > > > > root@10:~#
>> > > > >
>> > > > >
>> > > > > So, I wanted to know what are the conditions for which
>> > > > > setting
>> > > > > smp_affinity for an IRQ will work ?
>> > > > >
>> > > > > Is there any way by which I can set CPU affinity to a GPIO ->
>> > > > > IRQ ?
>> > > > > Whether, irq_set_affinity_hint() will work in this case ?
>> > > >
>> > > > IRQ affinity is only supported where interrupts are _directly_
>> > > > wired to
>> > > > the GIC. It's the GIC which does the interrupt steering to the
>> > > > CPU
>> > > > cores.
>> > > >
>> > > > Interrupts on downstream interrupt controllers (such as GPCV2)
>> > > > have no
>> > > > ability to be directed independently to other CPUs - the only
>> > > > possible
>> > > > way to change the mapping is to move _all_ interrupts on that
>> > > > controller,
>> > > > and any downstream chained interrupts at GIC level.
>> > > >
>> > > > Hence why Interrupt 295 has no irq_set_affinity function: there
>> > > > is no way
>> > > > for the interrupt controller itself to change the affinity of
>> > > > the input
>> > > > interrupt.
>> > >
>> > > The GPCv2 though is a secondary IRQ controller which has a 1:1
>> > > mapping
>> > > of its input IRQs to the upstream GIC IRQ lines. Affinity can
>> > > thus be
>> > > handled by forwarding the request to the GIC by
>> > > irq_chip_set_affinity_parent().
>> > >
>> > > As this is handled correctly in the upstream kernel since the
>> > > first
>> > > commit introducing support for the GPCv2, it seems the issue is
>> > > only
>> > > present in some downstream kernel.
>> > >
>> >
>> > OK. Thanks so much for your reply.
>> >
>> > I saw some of the drivers using irq_set_affinity_hint() to force
>> > the
>> > IRQ affinity to a particular CPU.
>> > This is the sample:
>> > {
>> > cpumask_clear(mask);
>> > cpumask_set_cpu(cpu, mask);
>> > irq_set_affinity_hint(irq, mask);
>> > }
>> >
>> > Whether this logic will work for a particular GPIO pin ?
>> >
>> >
>> > > Regards,
>> > > Lucas
On Mon, May 14, 2018 at 7:58 PM, Pintu Kumar <[email protected]> wrote:
>
> On Mon, May 14, 2018 at 6:41 PM, Lucas Stach <[email protected]> wrote:
> > Am Montag, den 14.05.2018, 17:42 +0530 schrieb Pintu Kumar:
> >> Hi,
> >>
> >> Is there any work around possible to set IRQ affinity for some GPIO
> >> interrupt ?
> >> How to avoid CPU0 to receive the current GPIO interrupt ?
> >> How do we assign GPIO interrupts to any CPU other than CPU0 ?
> >> Is it possible to isolate CPU0 for a sometime, from my GPIO driver so
> >> that GPIO interrupt can be served by another CPU ?
> >>
> >> Need your inputs to decide whether it is still possible to set
> >> affinity for GPIO interrupt, or its impossible ?
> >
> > This is not possible. The GPIO IRQs are aggregated into one GPC/GIC IRQ
> > line per GPIO bank, so it is not possible to change affinity of a
> > single GPIO interrupt to another CPU.
>
> OK. Thanks for your confirmation.
>
> > Best we could do is change the
> > affinity of the whole bank,
>
Hi,
I found that the driver is responsible for setting GPIO bank in i.MX7:
https://elixir.bootlin.com/linux/v4.2/source/drivers/gpio/gpio-mxc.c
However I still dont know how to set the cpumask for one of the GPIO Bank.
From this link, it seems it is possible to set affinity for a GPIO IRQ.
https://community.nxp.com/thread/303144
But when I try it form my GPIO138 (GPIO5_IO10) it did not help.
So, as you said, I wanted to change affinity for the whole GPIO bank and try it.
Please give me some pointers.
Thanks
> OK. How can we do this on the fly from my driver code.
> If you have any reference please let me know.
> This is required only for experimental purpose to prove the point to be mgmt.
> My idea is, from the driver, change the affinity of the whole bank.
> So, the GPIO interrupt can be delivered on to this specific CPU bank.
> Once I am done, I will revert back to the old bank.
> Please give me some hint on how to do this from my kernel module....
>
>
> > but given the limited usefulness of
> > something like that, nobody bothered to implement such a thing.
> >
> > Regards,
> > Lucas
> >
> >>
> >>
> >> On Fri, May 11, 2018 at 8:07 PM, Pintu Kumar <[email protected]>
> >> wrote:
> >> > On Fri, May 11, 2018 at 6:34 PM, Lucas Stach <[email protected]
> >> > e> wrote:
> >> > > Am Freitag, den 11.05.2018, 13:39 +0100 schrieb Russell King -
> >> > > ARM Linux:
> >> > > > On Fri, May 11, 2018 at 05:07:37PM +0530, Pintu Kumar wrote:
> >> > > > > Hi,
> >> > > > >
> >> > > > > I need one help.
> >> > > > > I am using i.MX7 Sabre board with kernel version 4.1.15
> >> > > > >
> >> > > > > Let's say I am interested in GPIO number: 21
> >> > > > > I wanted to set CPU affinity for particular GPIO->IRQ number,
> >> > > > > so I
> >> > > > > tried the below steps:
> >> > > > > root@10:~# echo 21 > /sys/class/gpio/export
> >> > > > > root@10:~# echo "rising" > /sys/class/gpio/gpio21/edge
> >> > > > > root@10:~# cat /proc/interrupts | grep 21
> >> > > > > 47: 0 0 gpio-mxc 21 Edge gpiolib
> >> > > > > root@10:~# cat /sys/class/gpio/gpio21/direction
> >> > > > > in
> >> > > > > root@10:~# cat /proc/irq/47/smp_affinity
> >> > > > > 3
> >> > > > > root@10:~# echo 2 > /proc/irq/47/smp_affinity
> >> > > > > -bash: echo: write error: Input/output error
> >> > > > >
> >> > > > > But I get input/output error.
> >> > > > > When I debug further, found that irq_can_set_affinity is
> >> > > > > returning 0:
> >> > > > > [ 0.000000] genirq: irq_can_set_affinity (0): balance: 1,
> >> > > > > irq_data.chip: a81b7e48, irq_set_affinity: (null)
> >> > > > > [ 0.000000] write_irq_affinity: FAIL
> >> > > > >
> >> > > > > I also tried first setting /proc/irq/default_smp_affinity to
> >> > > > > 2 (from 3).
> >> > > > > This change is working, but the smp_affinity setting for the
> >> > > > > new IRQ
> >> > > > > is not working.
> >> > > > >
> >> > > > > When I try to set smp_affinity for mmc0, then it works.
> >> > > > > # cat /proc/interrupts | grep mmc
> >> > > > > 295: 55 0 GPCV2 22 Edge mmc0
> >> > > > > 296: 0 0 GPCV2 23 Edge mmc1
> >> > > > > 297: 52 0 GPCV2 24 Edge mmc2
> >> > > > >
> >> > > > > root@10:~# echo 2 > /proc/irq/295/smp_affinity
> >> > > > > root@10:~#
> >> > > > >
> >> > > > >
> >> > > > > So, I wanted to know what are the conditions for which
> >> > > > > setting
> >> > > > > smp_affinity for an IRQ will work ?
> >> > > > >
> >> > > > > Is there any way by which I can set CPU affinity to a GPIO ->
> >> > > > > IRQ ?
> >> > > > > Whether, irq_set_affinity_hint() will work in this case ?
> >> > > >
> >> > > > IRQ affinity is only supported where interrupts are _directly_
> >> > > > wired to
> >> > > > the GIC. It's the GIC which does the interrupt steering to the
> >> > > > CPU
> >> > > > cores.
> >> > > >
> >> > > > Interrupts on downstream interrupt controllers (such as GPCV2)
> >> > > > have no
> >> > > > ability to be directed independently to other CPUs - the only
> >> > > > possible
> >> > > > way to change the mapping is to move _all_ interrupts on that
> >> > > > controller,
> >> > > > and any downstream chained interrupts at GIC level.
> >> > > >
> >> > > > Hence why Interrupt 295 has no irq_set_affinity function: there
> >> > > > is no way
> >> > > > for the interrupt controller itself to change the affinity of
> >> > > > the input
> >> > > > interrupt.
> >> > >
> >> > > The GPCv2 though is a secondary IRQ controller which has a 1:1
> >> > > mapping
> >> > > of its input IRQs to the upstream GIC IRQ lines. Affinity can
> >> > > thus be
> >> > > handled by forwarding the request to the GIC by
> >> > > irq_chip_set_affinity_parent().
> >> > >
> >> > > As this is handled correctly in the upstream kernel since the
> >> > > first
> >> > > commit introducing support for the GPCv2, it seems the issue is
> >> > > only
> >> > > present in some downstream kernel.
> >> > >
> >> >
> >> > OK. Thanks so much for your reply.
> >> >
> >> > I saw some of the drivers using irq_set_affinity_hint() to force
> >> > the
> >> > IRQ affinity to a particular CPU.
> >> > This is the sample:
> >> > {
> >> > cpumask_clear(mask);
> >> > cpumask_set_cpu(cpu, mask);
> >> > irq_set_affinity_hint(irq, mask);
> >> > }
> >> >
> >> > Whether this logic will work for a particular GPIO pin ?
> >> >
>
> >> >
> >> > > Regards,
> >> > > Lucas
Dear Lucas,
Can you give me some pointers on how to set affinity for entire GPIO Bank.
Currently I am exploring drivers/gpio/gpio-mxc.c to find out how the
GPIO banks are set up.
I also found that affinity can be set using: desc->irq_data.affinity,
may be by using cpumask_copy(...).
But still I am not familiar with this.
So, I need your help.
Thank You!
Regards,
Pintu
On Thu, May 17, 2018 at 6:58 PM, Pintu Kumar <[email protected]> wrote:
> On Mon, May 14, 2018 at 7:58 PM, Pintu Kumar <[email protected]> wrote:
>>
>> On Mon, May 14, 2018 at 6:41 PM, Lucas Stach <[email protected]> wrote:
>> > Am Montag, den 14.05.2018, 17:42 +0530 schrieb Pintu Kumar:
>> >> Hi,
>> >>
>> >> Is there any work around possible to set IRQ affinity for some GPIO
>> >> interrupt ?
>> >> How to avoid CPU0 to receive the current GPIO interrupt ?
>> >> How do we assign GPIO interrupts to any CPU other than CPU0 ?
>> >> Is it possible to isolate CPU0 for a sometime, from my GPIO driver so
>> >> that GPIO interrupt can be served by another CPU ?
>> >>
>> >> Need your inputs to decide whether it is still possible to set
>> >> affinity for GPIO interrupt, or its impossible ?
>> >
>> > This is not possible. The GPIO IRQs are aggregated into one GPC/GIC IRQ
>> > line per GPIO bank, so it is not possible to change affinity of a
>> > single GPIO interrupt to another CPU.
>>
>> OK. Thanks for your confirmation.
>>
>> > Best we could do is change the
>> > affinity of the whole bank,
>>
>
> Hi,
>
> I found that the driver is responsible for setting GPIO bank in i.MX7:
> https://elixir.bootlin.com/linux/v4.2/source/drivers/gpio/gpio-mxc.c
>
> However I still dont know how to set the cpumask for one of the GPIO Bank.
>
> From this link, it seems it is possible to set affinity for a GPIO IRQ.
> https://community.nxp.com/thread/303144
>
> But when I try it form my GPIO138 (GPIO5_IO10) it did not help.
>
> So, as you said, I wanted to change affinity for the whole GPIO bank and try it.
> Please give me some pointers.
>
> Thanks
>
>
>> OK. How can we do this on the fly from my driver code.
>> If you have any reference please let me know.
>> This is required only for experimental purpose to prove the point to be mgmt.
>> My idea is, from the driver, change the affinity of the whole bank.
>> So, the GPIO interrupt can be delivered on to this specific CPU bank.
>> Once I am done, I will revert back to the old bank.
>> Please give me some hint on how to do this from my kernel module....
>>
>>
>> > but given the limited usefulness of
>> > something like that, nobody bothered to implement such a thing.
>> >
>> > Regards,
>> > Lucas
>> >
>> >>
>> >>
>> >> On Fri, May 11, 2018 at 8:07 PM, Pintu Kumar <[email protected]>
>> >> wrote:
>> >> > On Fri, May 11, 2018 at 6:34 PM, Lucas Stach <[email protected]
>> >> > e> wrote:
>> >> > > Am Freitag, den 11.05.2018, 13:39 +0100 schrieb Russell King -
>> >> > > ARM Linux:
>> >> > > > On Fri, May 11, 2018 at 05:07:37PM +0530, Pintu Kumar wrote:
>> >> > > > > Hi,
>> >> > > > >
>> >> > > > > I need one help.
>> >> > > > > I am using i.MX7 Sabre board with kernel version 4.1.15
>> >> > > > >
>> >> > > > > Let's say I am interested in GPIO number: 21
>> >> > > > > I wanted to set CPU affinity for particular GPIO->IRQ number,
>> >> > > > > so I
>> >> > > > > tried the below steps:
>> >> > > > > root@10:~# echo 21 > /sys/class/gpio/export
>> >> > > > > root@10:~# echo "rising" > /sys/class/gpio/gpio21/edge
>> >> > > > > root@10:~# cat /proc/interrupts | grep 21
>> >> > > > > 47: 0 0 gpio-mxc 21 Edge gpiolib
>> >> > > > > root@10:~# cat /sys/class/gpio/gpio21/direction
>> >> > > > > in
>> >> > > > > root@10:~# cat /proc/irq/47/smp_affinity
>> >> > > > > 3
>> >> > > > > root@10:~# echo 2 > /proc/irq/47/smp_affinity
>> >> > > > > -bash: echo: write error: Input/output error
>> >> > > > >
>> >> > > > > But I get input/output error.
>> >> > > > > When I debug further, found that irq_can_set_affinity is
>> >> > > > > returning 0:
>> >> > > > > [ 0.000000] genirq: irq_can_set_affinity (0): balance: 1,
>> >> > > > > irq_data.chip: a81b7e48, irq_set_affinity: (null)
>> >> > > > > [ 0.000000] write_irq_affinity: FAIL
>> >> > > > >
>> >> > > > > I also tried first setting /proc/irq/default_smp_affinity to
>> >> > > > > 2 (from 3).
>> >> > > > > This change is working, but the smp_affinity setting for the
>> >> > > > > new IRQ
>> >> > > > > is not working.
>> >> > > > >
>> >> > > > > When I try to set smp_affinity for mmc0, then it works.
>> >> > > > > # cat /proc/interrupts | grep mmc
>> >> > > > > 295: 55 0 GPCV2 22 Edge mmc0
>> >> > > > > 296: 0 0 GPCV2 23 Edge mmc1
>> >> > > > > 297: 52 0 GPCV2 24 Edge mmc2
>> >> > > > >
>> >> > > > > root@10:~# echo 2 > /proc/irq/295/smp_affinity
>> >> > > > > root@10:~#
>> >> > > > >
>> >> > > > >
>> >> > > > > So, I wanted to know what are the conditions for which
>> >> > > > > setting
>> >> > > > > smp_affinity for an IRQ will work ?
>> >> > > > >
>> >> > > > > Is there any way by which I can set CPU affinity to a GPIO ->
>> >> > > > > IRQ ?
>> >> > > > > Whether, irq_set_affinity_hint() will work in this case ?
>> >> > > >
>> >> > > > IRQ affinity is only supported where interrupts are _directly_
>> >> > > > wired to
>> >> > > > the GIC. It's the GIC which does the interrupt steering to the
>> >> > > > CPU
>> >> > > > cores.
>> >> > > >
>> >> > > > Interrupts on downstream interrupt controllers (such as GPCV2)
>> >> > > > have no
>> >> > > > ability to be directed independently to other CPUs - the only
>> >> > > > possible
>> >> > > > way to change the mapping is to move _all_ interrupts on that
>> >> > > > controller,
>> >> > > > and any downstream chained interrupts at GIC level.
>> >> > > >
>> >> > > > Hence why Interrupt 295 has no irq_set_affinity function: there
>> >> > > > is no way
>> >> > > > for the interrupt controller itself to change the affinity of
>> >> > > > the input
>> >> > > > interrupt.
>> >> > >
>> >> > > The GPCv2 though is a secondary IRQ controller which has a 1:1
>> >> > > mapping
>> >> > > of its input IRQs to the upstream GIC IRQ lines. Affinity can
>> >> > > thus be
>> >> > > handled by forwarding the request to the GIC by
>> >> > > irq_chip_set_affinity_parent().
>> >> > >
>> >> > > As this is handled correctly in the upstream kernel since the
>> >> > > first
>> >> > > commit introducing support for the GPCv2, it seems the issue is
>> >> > > only
>> >> > > present in some downstream kernel.
>> >> > >
>> >> >
>> >> > OK. Thanks so much for your reply.
>> >> >
>> >> > I saw some of the drivers using irq_set_affinity_hint() to force
>> >> > the
>> >> > IRQ affinity to a particular CPU.
>> >> > This is the sample:
>> >> > {
>> >> > cpumask_clear(mask);
>> >> > cpumask_set_cpu(cpu, mask);
>> >> > irq_set_affinity_hint(irq, mask);
>> >> > }
>> >> >
>> >> > Whether this logic will work for a particular GPIO pin ?
>> >> >
>
>
>>
>> >> >
>> >> > > Regards,
>> >> > > Lucas