Re: [Intel-gfx] [PATCH 4/4] DO_NOT_MERGE: drm/i915/display: Enable PSR2 selective fetch by default

[Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>]

On 8/3/21 8:18 PM, Souza, Jose wrote:
> On Tue, 2021-08-03 at 14:17 +0300, Gwan-gyeong Mun wrote:
>>
>> On 7/31/21 3:10 AM, José Roberto de Souza wrote:
>>> Only to execute tests with PSR2 selective fetch enabled and check what
>>> is broken.
>>>
>>> IGT tests know to fail with this:
>>> - kms_cursor_legacy: all tests that checks if evasion happend, I have
>>> fix for it making cursor_slowpath() returns true for display 12+.
>>>
>>> - kms_psr2_su: The pageflip test, it needs to have the damage clip set
>>> otherwise it will update the whole screen and the selective blocks
>>> will not match with expected.
>>>
>> kms_psr2_su is a test case for intel PSR2 HW tracking and kms_psr2_sf is
>> used as a test for intel PSR2 manual tracking. Is it necessary to modify
>> kms_psr2_su for testing PSR2 manual tracking?
> 
> kms_psr2_su is to test that PSR2 is sending selective updates, just adding a couple of lines we can make it work with selective fetch.
> 
>>> - kms_psr: psr2_*_(mmap_gtt, mmap_cpu, blt and render), all those
>>> tests should be dropped or skipped for display 12+.
>>>
>> Could you explain in more detail why we need to skip on display 12+?
> 
> This are stuff that would end up calling intel_psr_invalidate/flush().
> 

Thanks for the explanation.
And there is an issue confirmed in local tests, so I leave additional 
comments.
>>
>>> Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
>>> ---
>>>    drivers/gpu/drm/i915/display/intel_psr.c | 9 ---------
>>>    drivers/gpu/drm/i915/i915_params.h       | 2 +-
>>>    2 files changed, 1 insertion(+), 10 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
>>> index 894a2d35668a2..e128f0c2aeecc 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_psr.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
>>> @@ -877,15 +877,6 @@ static bool intel_psr2_config_valid(struct intel_dp *intel_dp,
>>>    return false;
>>>    }
>>>
>>> -/*
>>> - * We are missing the implementation of some workarounds to enabled PSR2
>>> - * in Alderlake_P, until ready PSR2 should be kept disabled.
>>> - */
>>> -if (IS_ALDERLAKE_P(dev_priv)) {
>>> -drm_dbg_kms(&dev_priv->drm, "PSR2 is missing the implementation of workarounds\n");
>>> -return false;
>>> -}
>>> -
>>>    if (!transcoder_has_psr2(dev_priv, crtc_state->cpu_transcoder)) {
>>>    drm_dbg_kms(&dev_priv->drm,
>>>        "PSR2 not supported in transcoder %s\n",
>>> diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
>>> index f27eceb82c0f5..8d725b64592d8 100644
>>> --- a/drivers/gpu/drm/i915/i915_params.h
>>> +++ b/drivers/gpu/drm/i915/i915_params.h
>>> @@ -55,7 +55,7 @@ struct drm_printer;
>>>    param(int, enable_fbc, -1, 0600) \
>>>    param(int, enable_psr, -1, 0600) \
>>>    param(bool, psr_safest_params, false, 0400) \
>>> -param(bool, enable_psr2_sel_fetch, false, 0400) \
>>> +param(bool, enable_psr2_sel_fetch, true, 0400) \
If we do not modify this part and do not enable it by default at boot 
time as shown in the original code below,
param(bool, enable_psr2_sel_fetch, false, 0400) \

when we execute the kms_psr2_sf test case of igt, the FIFO underrun as 
below still occurs.

i915 0000:00:02.0: [drm] *ERROR* CPU pipe A FIFO underrun: port,transcoder,

When PSR2 panel is used, PSR1 is enabled by default when 
enable_psr2_sel_fetch is not enabled by default.
And when kms_psr2_sf is executed, the mode is changed to PSR2, and when 
kms_psr2_sf is terminated, PSR2 is deactivated and PSR1 is re-enabled. 
At this point. I suspect there is a problem.

>>>    param(int, disable_power_well, -1, 0400) \
>>>    param(int, enable_ips, 1, 0600) \
>>>    param(int, invert_brightness, 0, 0600) \
>>>
>