[Intel-gfx] [PATCH] drm/i915/glk: Don't allow 12 bpc when htotal is too big

[Jani Nikula]

On Mon, 24 Apr 2017, Ander Conselvan De Oliveira <conselvan2 at gmail.com> wrote:
> On Mon, 2017-04-24 at 13:47 +0300, Ander Conselvan de Oliveira wrote:
>> Display workaround #1139 for Geminilake instructs us to restrict HDMI
>> to 8 bpc when htotal is greater than 5460. Otherwise, the pipe is unable
>> to generate a proper signal and is left in a state where corruption is
>> seen with other modes.
>> 
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100440
>> Cc: Shashank Sharma <shashank.sharma at intel.com>
>> Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira at intel.com>
>
> Perhaps this should have
>
> Fixes: 14292b7ff86f ("drm/i915: allow HDMI 2.0 clock rates")
>
> since it is only after that patch that the issue would be exposed, even though
> is not the cause for it. Jani?

I don't mind/care too much either way, because it's only GLK <= A1.

BR,
Jani.



>
> Ander
>
>> ---
>>  drivers/gpu/drm/i915/intel_hdmi.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>> 
>> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
>> index 6efc3cb..52f0b2d 100644
>> --- a/drivers/gpu/drm/i915/intel_hdmi.c
>> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
>> @@ -1327,6 +1327,11 @@ static bool hdmi_12bpc_possible(struct intel_crtc_state *crtc_state)
>>  			return false;
>>  	}
>>  
>> +	/* Display Wa #1139 */
>> +	if (IS_GLK_REVID(dev_priv, 0, GLK_REVID_A1) &&
>> +	    crtc_state->base.adjusted_mode.htotal > 5460)
>> +		return false;
>> +
>>  	return true;
>>  }
>>  

-- 
Jani Nikula, Intel Open Source Technology Center