[PATCH v2 1/2] drm: Add GPU reset sysfs event

[Sharma, Shashank]

On 3/10/2022 6:10 PM, Rob Clark wrote:
> On Thu, Mar 10, 2022 at 8:21 AM Sharma, Shashank
> <shashank.sharma at amd.com> wrote:
>>
>>
>>
>> On 3/10/2022 4:24 PM, Rob Clark wrote:
>>> On Thu, Mar 10, 2022 at 1:55 AM Christian König
>>> <ckoenig.leichtzumerken at gmail.com> wrote:
>>>>
>>>>
>>>>
>>>> Am 09.03.22 um 19:12 schrieb Rob Clark:
>>>>> On Tue, Mar 8, 2022 at 11:40 PM Shashank Sharma
>>>>> <contactshashanksharma at gmail.com> wrote:
>>>>>> From: Shashank Sharma <shashank.sharma at amd.com>
>>>>>>
>>>>>> This patch adds a new sysfs event, which will indicate
>>>>>> the userland about a GPU reset, and can also provide
>>>>>> some information like:
>>>>>> - process ID of the process involved with the GPU reset
>>>>>> - process name of the involved process
>>>>>> - the GPU status info (using flags)
>>>>>>
>>>>>> This patch also introduces the first flag of the flags
>>>>>> bitmap, which can be appended as and when required.
>>>>> Why invent something new, rather than using the already existing devcoredump?
>>>>
>>>> Yeah, that's a really valid question.
>>>>
>>>>> I don't think we need (or should encourage/allow) something drm
>>>>> specific when there is already an existing solution used by both drm
>>>>> and non-drm drivers.  Userspace should not have to learn to support
>>>>> yet another mechanism to do the same thing.
>>>>
>>>> Question is how is userspace notified about new available core dumps?
>>>
>>> I haven't looked into it too closely, as the CrOS userspace
>>> crash-reporter already had support for devcoredump, so it "just
>>> worked" out of the box[1].  I believe a udev event is what triggers
>>> the crash-reporter to go read the devcore dump out of sysfs.
>>
>> I had a quick look at the devcoredump code, and it doesn't look like
>> that is sending an event to the user, so we still need an event to
>> indicate a GPU reset.
> 
> There definitely is an event to userspace, I suspect somewhere down
> the device_add() path?
> 

Let me check that out as well, hope that is not due to a driver-private 
event for GPU reset, coz I think I have seen some of those in a few DRM 
drivers.

- Shashank

> BR,
> -R