Re: [PATCH] drm/i915: don't try using training pattern 3 on pre-haswell

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 29 Oct 2014, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Wed, Oct 29, 2014 at 10:23:50AM +0200, Jani Nikula wrote:
>> On Wed, 29 Oct 2014, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
>> > On Wed, Oct 29, 2014 at 05:02:50PM +1000, Dave Airlie wrote:
>> >> From: Dave Airlie <airlied@redhat.com>
>> >> 
>> >> Ivybridge + 30" monitor prints a drm error on every modeset, since
>> >> IVB doesn't support DP3 we should even bother trying to use it.
>> >> 
>> >> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> (on irc)
>> >> Signed-off-by: Dave Airlie <airlied@redhat.com>
>> >> ---
>> >>  drivers/gpu/drm/i915/intel_dp.c | 4 +++-
>> >>  1 file changed, 3 insertions(+), 1 deletion(-)
>> >> 
>> >> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>> >> index f6a3fdd..87cfb92 100644
>> >> --- a/drivers/gpu/drm/i915/intel_dp.c
>> >> +++ b/drivers/gpu/drm/i915/intel_dp.c
>> >> @@ -3547,13 +3547,15 @@ intel_dp_start_link_train(struct intel_dp *intel_dp)
>> >>  void
>> >>  intel_dp_complete_link_train(struct intel_dp *intel_dp)
>> >>  {
>> >> +	struct drm_encoder *encoder = &dp_to_dig_port(intel_dp)->base.base;
>> >> +	struct drm_device *dev = encoder->dev;
>> >>  	bool channel_eq = false;
>> >>  	int tries, cr_tries;
>> >>  	uint32_t DP = intel_dp->DP;
>> >>  	uint32_t training_pattern = DP_TRAINING_PATTERN_2;
>> >>  
>> >>  	/* Training Pattern 3 for HBR2 ot 1.2 devices that support it*/
>> >> -	if (intel_dp->link_bw == DP_LINK_BW_5_4 || intel_dp->use_tps3)
>> >> +	if ((intel_dp->link_bw == DP_LINK_BW_5_4 || intel_dp->use_tps3) && !HAS_DDI(dev))
>> >
>> > CHV has pattern 3.
>> 
>> Is "supports tps3" the same set of platforms as "supports 5.4 Gbps"? We
>> should abstract the check from intel_dp_max_link_bw.
>
> Not quite. HSW-ULX supports pattern 3 even though it doesn't do 5.4 Gbps.

How about [1] instead? I forgot --in-reply-to, sorry.

BR,
Jani.


[1] http://mid.gmane.org/1414573406-17071-1-git-send-email-jani.nikula@intel.com


-- 
Jani Nikula, Intel Open Source Technology Center
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