[Intel-gfx] [PATCH v2 2/2] drm/i915/bdw: Fix DP_AUX_CH_CTL_TIME_OUT setting

[Ausmus, James]

On Wed, Oct 4, 2017 at 3:54 PM, Runyan, Arthur J
<arthur.j.runyan at intel.com> wrote:
> I think the failure was with one particularly slow eDP panel, but it is safer to apply this to all ports.
>

Thanks Art. Anyone else have thoughts/comments on this, or should this
be good for merge now?

Thanks!

-James

> -----Original Message-----
> From: Vivi, Rodrigo
> Sent: Wednesday, 4 October, 2017 1:25 PM
> To: Ausmus, James <james.ausmus at intel.com>
> Cc: intel-gfx at lists.freedesktop.org; ville.syrjala at linux.intel.com; jani.nikula at linux.intel.com; Runyan, Arthur J <arthur.j.runyan at intel.com>; ben at bwidawsk.net
> Subject: Re: [PATCH v2 2/2] drm/i915/bdw: Fix DP_AUX_CH_CTL_TIME_OUT setting
>
> On Wed, Oct 04, 2017 at 08:09:22PM +0000, James Ausmus wrote:
>> Per BSpec, 400us is "BDW+ Do not use this setting." - not just PORT_A.
>> Set BDW to 600us unconditionally.
>
> Besides that statement I also found on BSpec:
>
> "
> Workaround
> Project
> BDW, EXCLUDE(CHV)
> Set the Timeout timer value to at least 600us before initiating a transaction.
> "
>
> Also I tracked this on the log and arrived to commit 'a81a507d487c
> ("drm/i915/bdw: Change dp aux timeout to 600us on DDIA")'
>
> It seems during BDW enabling HW team found that need but only for port A
> and later they might have extended it and we never noticed.
>
> Ccin't Art and Ben here to see if they can comment on that.
>
> But I believe we should add this so
>
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
>
>>
>> v2:
>> -Split in to two patches (Rodrigo)
>>
>> Cc: Jani Nikula <jani.nikula at linux.intel.com>
>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> Signed-off-by: James Ausmus <james.ausmus 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 5b4c9484575b..df301e00d9d9 100644
>> --- a/drivers/gpu/drm/i915/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>> @@ -1019,7 +1019,7 @@ static uint32_t g4x_get_aux_send_ctl(struct intel_dp *intel_dp,
>>       else
>>               precharge = 5;
>>
>> -     if (IS_BROADWELL(dev_priv) && intel_dig_port->port == PORT_A)
>> +     if (IS_BROADWELL(dev_priv))
>>               timeout = DP_AUX_CH_CTL_TIME_OUT_600us;
>>       else
>>               timeout = DP_AUX_CH_CTL_TIME_OUT_400us;
>> --
>> 2.14.1
>>



-- 


James Ausmus