Re: [PATCH] drm/i915: Reset dpll_hw_state when selecting a new pll on hsw

[Gabriel Feceoru <gabriel.feceoru@intel.com>]

On 11.11.2015 16:21, Jani Nikula wrote:
> On Wed, 11 Nov 2015, Ander Conselvan De Oliveira <conselvan2@gmail.com> wrote:
>> On Tue, 2015-11-10 at 14:53 +0200, Jani Nikula wrote:
>>> Ander, Maarten, where are we with this? Is it horribly wrong to merge
>>> the original patch in this ever-growing and diverging thread?
>>
>> I think the patch as is will cause problems with DP, since we might clear the
>> pll selection made in hsw_dp_set_ddi_pll_sel(). I think the easy fix
>> disregarding the discussion in this thread is to drop another memset in
>>   intel_crt_compute_config(). Like this
>
>
> Ander, please post this as a proper patch for review.
>
> BR,
> Jani.

Hi,
I tested this patch on my system and I can confirm it fixes the original 
issue.
However there are a few memset in *_ddi_pll_select functions which might 
not be needed anymore. For instance I tried to remove the hsw one and 
didn't see any regression.

Regards,
Gabriel

>
>>
>> diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
>> index b84aaa0..ad099f3 100644
>> --- a/drivers/gpu/drm/i915/intel_crt.c
>> +++ b/drivers/gpu/drm/i915/intel_crt.c
>> @@ -278,6 +278,9 @@ static bool intel_crt_compute_config(struct intel_encoder
>> *encoder,
>>
>>          /* FDI must always be 2.7 GHz */
>>          if (HAS_DDI(dev)) {
>> +               memset(&pipe_config->dpll_hw_state, 0,
>> +                      sizeof(pipe_config->dpll_hw_state));
>> +
>>                  pipe_config->ddi_pll_sel = PORT_CLK_SEL_SPLL;
>>                  pipe_config->port_clock = 135000 * 2;
>>          }
>>
>> Ander
>
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