Re: [PATCH v2 0/3] drm/amdgpu: Remove in_interrupt() usage.

["Christian König" <christian.koenig@amd.com>]

Hi Sebastian,

Am 10.03.21 um 18:47 schrieb Sebastian Andrzej Siewior:
> On 2021-02-09 18:43:54 [+0100], Christian König wrote:
>> to be honest I'm thinking about that for quite some time now and I don't
>> think that this is possible without a severe rewrite of the driver.
>>
>> The problem is simply that we have a lot of functions which deal with
>> hardware handling independent of the context. But how registers are accessed
>> needs to be different depending if your are in the interrupt handler or not.
>>
>> You would need to push the information if we are coming in from the
>> interrupt handler through a > 10 function calls.
>>
>> I don't think that this is feasible nor good design.
> Yeah, that is what I saw and didn't even try.

I also have no idea where to start.

> The possible backtrace (at the bottom of this email) is this a correct
> assumption?

It's one of many, yes. But the real complicated once are in the CS UAPI 
and interrupt handling.

>
> Another quick question: You acked my three-patch series. I don't see it
> in the next tree as of today. Is there anything for me to do?

Alex usually picks them up into amd-staging-drm-next which is then 
merged into drm-next.

Regards,
Christian.

>
>> Regards,
>> Christian.
>>
>> Am 09.02.21 um 17:53 schrieb Sebastian Andrzej Siewior:
>>> On 2021-02-09 13:50:31 [+0100], Christian König wrote:
>>>> Reviewed-by: Christian König <christian.koenig@amd.com> for the series.
>>> Thank you.
>>> Any chance you could give me a hand with the remaining three users
>>> within the amdgpu driver? I don't know if the in_interrupt() check can
>>> be limited to certain callers.
>>> What I noticed while tracing v5.10 is this:
>>>
>>> |             Xorg-2257    [007] d... 57261.620043: amdgpu_device_wreg: 0x699f, 0x00001bcf, 0x00000100
>>> |  => trace_event_raw_event_amdgpu_device_wreg
>>> |  => amdgpu_device_wreg.part.0
>>> |  => dce110_arm_vert_intr
>>> |  => dce110_vblank_set
>>> |  => dm_enable_vblank
>>> |  => drm_vblank_enable
>>> |  => drm_vblank_get
>>> |  => drm_wait_vblank_ioctl
>>> |  => drm_ioctl_kernel
>>> |  => drm_ioctl
>>> |  => amdgpu_drm_ioctl
>>> |  => __x64_sys_ioctl
>>> |  => do_syscall_64
>>> |  => entry_SYSCALL_64_after_hwframe
>>>
>>> I think that amdgpu_device_wreg() -> amdgpu_kiq_wreg() could be invoked.
>>> It doesn't here because amdgpu_sriov_runtime() is false.
>>> The trace says `d' which means interrupts are disabled but
>>> in_interrupt() will return false in this case (no IRQ/softirq).
>>>
>>> Sebastian
> Sebastian

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