[Intel-gfx] [PATCH] drm/i915/edp: Increase T12 panel delay to 900 ms to fix DP AUX CH timeouts

[Clint Taylor]

On 08/16/2017 02:19 PM, Rodrigo Vivi wrote:
> It seems this quirk is randomly masking the real issue.
It could be masking the real issue. The most likely cause of this issue 
is a slow power fall off to the panel when the PPS requests power-off. 
We would need physical access to the platform itself to confirm by 
measuring the power fall off with a scope. We could also instrument a 
Gen9 platform and confirm the panel power sequencer is working 
correctly. However that will not show why this particular tcon appears 
to no longer communicate after a reset.

-Clint



>
> On Wed, Aug 16, 2017 at 12:35 PM, Manasi Navare
> <manasi.d.navare at intel.com> wrote:
>> Hi Daniel/Clint,
>>
>> Could you review this one, we need this patch to get pushed
>> to drm-tip so that we can see if SKL 6700hq is stable with this patch.
>> Thanks a lot in advanvce!
>>
>> Regards
>> Manasi
>>
>> On Tue, Aug 15, 2017 at 11:59:51AM -0700, Manasi Navare wrote:
>>> This patch fixes the DP AUX CH timeouts observed during CI runs causing
>>> CI Failures on a specific PCI device. This issue was fixed previously
>>> by adding a quirk but looks like we need to increase this delay even more
>>> in order to get rid all the DP AUX CH timeouts.
>>>
>>> Fixes: c99a259b4b5192ba ("drm/i915/edp: Add a T12 panel delay quirk to fix
>>> DP AUX CH timeouts")
>>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101144
>>> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
>>> Cc: Clinton Taylor <clinton.a.taylor at intel.com>
>>> Cc: Daniel Vetter <daniel.vetter at intel.com>
>>> Cc: Tomi Sarvela <tomi.p.sarvela at intel.com>
>>> ---
>>>   drivers/gpu/drm/i915/intel_dp.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>>> index 5ba8366..c4d8afa 100644
>>> --- a/drivers/gpu/drm/i915/intel_dp.c
>>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>>> @@ -5246,7 +5246,7 @@ intel_dp_init_panel_power_sequencer(struct drm_device *dev,
>>>         * seems sufficient to avoid this problem.
>>>         */
>>>        if (dev_priv->quirks & QUIRK_INCREASE_T12_DELAY) {
>>> -             vbt.t11_t12 = max_t(u16, vbt.t11_t12, 800 * 10);
>>> +             vbt.t11_t12 = max_t(u16, vbt.t11_t12, 900 * 10);
>>>                DRM_DEBUG_KMS("Increasing T12 panel delay as per the quirk to %d\n",
>>>                              vbt.t11_t12);
>>>        }
>>> --
>>> 2.1.4
>>>
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
>