Re: [PATCH 2/2] drm/i915: Don't treat FLR resets as errors

[Nirmoy Das <nirmoy.das@linux.intel.com>]

Hi Andi,

On 5/21/2024 12:56 PM, Andi Shyti wrote:
> Hi Nirmoy,
>
> On Fri, May 17, 2024 at 10:13:37PM +0200, Nirmoy Das wrote:
>> Hi Andi,
>>
>> On 5/17/2024 9:34 PM, Andi Shyti wrote:
>>
>>      Hi Nirmoy,
>>
>>      On Fri, May 17, 2024 at 04:00:02PM +0200, Nirmoy Das wrote:
>>
>>          On 5/17/2024 1:25 PM, Andi Shyti wrote:
>>
>>              If we timeout while waiting for an FLR reset, there is nothing we
>>              can do and i915 doesn't have any control on it. In any case the
>>              system is still perfectly usable
>>
>>          If a FLR reset fails then we will have a dead GPU, I don't think the GPU is
>>          usable without a cold reboot.
>>
>>      fact is that the GPU keeps going and even though the timeout has
>>      expired, the system moves to the next phase.
>>
>> The current test might look like it is has passed, but if you look into the
>> subsequent tests you can see a dead GPU:
>>
>> <7>[  369.168121] pci 0000:00:02.0: [drm:intel_uncore_fini_mmio [i915]] Triggering Driver-FLR
>> <3>[  372.170189] pci 0000:00:02.0: [drm] *ERROR* Driver-FLR-teardown wait completion failed! -110
>> <7>[  372.437630] [IGT] i915_selftest: finished subtest requests, SUCCESS
>> <7>[  372.438356] [IGT] i915_selftest: starting dynamic subtest migrate
>> <5>[  373.110580] Setting dangerous option live_selftests - tainting kernel
>> <3>[  373.183499] i915 0000:00:02.0: Unable to change power state from D0 to D0, device inaccessible
>> <3>[  373.246921] i915 0000:00:02.0: [drm] *ERROR* Unrecognized display IP version 1023.255; disabling display.
>> <7>[  373.247130] i915 0000:00:02.0: [drm:intel_step_init [i915]] Using future steppings
>> <7>[  373.247716] i915 0000:00:02.0: [drm:intel_step_init [i915]] Using future steppings
>> <7>[  373.248263] i915 0000:00:02.0: [drm:intel_step_init [i915]] Using future display steppings
>> <7>[  373.251843] i915 0000:00:02.0: [drm:intel_gt_common_init_early [i915]] WOPCM: 2048K
>> <7>[  373.252505] i915 0000:00:02.0: [drm:intel_uc_init_early [i915]] GT0: enable_guc=3 (guc:yes submission:yes huc:no slpc:yes)
>> <7>[  373.253140] i915 0000:00:02.0: [drm:intel_gt_probe_all [i915]] GT0: Setting up Primary GT
>> <7>[  373.253556] i915 0000:00:02.0: [drm:intel_gt_probe_all [i915]] GT1: Setting up Standalone Media GT
>> <7>[  373.253941] i915 0000:00:02.0: [drm:intel_gt_common_init_early [i915]] WOPCM: 2048K
>> <7>[  373.254365] i915 0000:00:02.0: [drm:intel_uc_init_early [i915]] GT1: enable_guc=3 (guc:yes submission:yes huc:yes slpc:yes)
>> <3>[  375.256235] i915 0000:00:02.0: [drm] *ERROR* Device is non-operational; MMIO access returns 0xFFFFFFFF!
>> <3>[  375.259089] i915 0000:00:02.0: Device initialization failed (-5)
>> <3>[  375.260521] i915 0000:00:02.0: probe with driver i915 failed with error -5
>> <7>[  375.392209] [IGT] i915_selftest: finished subtest migrate, FAIL
>>
>> https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_14724/bat-arls-3/dmesg0.txt
> Are we sure this is dependent on the FLR reset?

Yes, while on FLR read into memory will return either 0/F.


>   There are cases
> when the FLR reset doesn't make any difference and in any case
> this error is completely ignored by the driver.

This happens at very late with no recovery possible and hope is module  
reload works.


>
> Perhaps we can change it to a warning?

I think it should be error. CI will still complain even on warning.


>
>>          This is a serious issue and should be report as an error.  I think we need
>>          to create a HW ticket to understand
>>
>>          why is FLR reset fails.
>>
>>      Maybe it takes longer and longer to reset. We've been sending
>>      several patches in the latest years to fix the timings.
>>
>> HW spec says 3 sec but we can try increasing it bit higher to try it out.
> We could go, then, with just patch 1 and see if it improves.

Does it help ? If helps then we can go ahead with increased timeout.


>   Also
> because, the FLR reset might also depend on the firmware.

Possible. In that case we should wait for firmware fix ?


Regards,

Nirmoy

>
> Thanks, Nirmoy,
> Andi