[Saucy][SRU][PATCH 1/1] (no-up) Revert "Revert "drm/i915: revert eDP bpp clamping code changes""

[Tim Gardner]

On 10/16/2013 02:06 PM, Joseph Salisbury wrote:
> On 10/16/2013 04:57 PM, Joseph Salisbury wrote:
>> BugLink: http://bugs.launchpad.net/bugs/1195483
>>
>> This reverts commit 657445fe8660100ad174600ebfa61536392b7624.
>>
>> Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
>> ---
>>   drivers/gpu/drm/i915/intel_dp.c |   18 ++++++++++++++----
>>   1 file changed, 14 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>> index 26e162b..ce933ad 100644
>> --- a/drivers/gpu/drm/i915/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>> @@ -709,10 +709,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
>>
>>   	/* Walk through all bpp values. Luckily they're all nicely spaced with 2
>>   	 * bpc in between. */
>> -	bpp = pipe_config->pipe_bpp;
>> -	if (is_edp(intel_dp) && dev_priv->vbt.edp_bpp)
>> -		bpp = min_t(int, bpp, dev_priv->vbt.edp_bpp);
>> -
>> +	bpp = min_t(int, 8*3, pipe_config->pipe_bpp);
>>   	for (; bpp >= 6*3; bpp -= 2*3) {
>>   		mode_rate = intel_dp_link_required(adjusted_mode->clock, bpp);
>>
>> @@ -763,6 +760,19 @@ found:
>>   			       &pipe_config->dp_m_n);
>>
>>   	intel_dp_set_clock(encoder, pipe_config, intel_dp->link_bw);
>> +	/*
>> +	 * XXX: We have a strange regression where using the vbt edp bpp value
>> +	 * for the link bw computation results in black screens, the panel only
>> +	 * works when we do the computation at the usual 24bpp (but still
>> +	 * requires us to use 18bpp). Until that's fully debugged, stay
>> +	 * bug-for-bug compatible with the old code.
>> +	 */
>> +	if (is_edp(intel_dp) && dev_priv->vbt.edp_bpp) {
>> +		DRM_DEBUG_KMS("clamping display bpc (was %d) to eDP (%d)\n",
>> +			      bpp, dev_priv->vbt.edp_bpp);
>> +		bpp = min_t(int, bpp, dev_priv->vbt.edp_bpp);
>> +	}
>> +	pipe_config->pipe_bpp = bpp;
>>
>>   	return true;
>>   }
>
> A proper fix is also being discussed upstream:
> https://bugzilla.kernel.org/show_bug.cgi?id=59841
>
> Maybe an alternative to this patch is to add something to the Saucy
> release notes until this is fixed upstream?
>
>

Joe - any upstream movement on this ?

-- 
Tim Gardner tim.gardner at canonical.com