[Intel-gfx] [PATCH 1/4] drm/i915: read dpcd 0 - 12 & link_status always

[Jani Nikula]

On Thu, 27 Aug 2015, Sivakumar Thulasimani <sivakumar.thulasimani at intel.com> wrote:
> From: "Thulasimani,Sivakumar" <sivakumar.thulasimani at intel.com>
>
> Compliance requires the driver to read dpcd register 0 to 12 and
> registers 0x200 to 0x205 to be read always.
> Current code performs dpcd read for short pulse interrupts only
> if the sink is enabled. This patch forces read for link status
> and registers 0 to 12.

While this seems a bit silly from the driver perspective, I don't see it
doing much harm either.

Note that We do read dpcd 0 to 14 no matter what the spec says.

Reviewed-by: Jani Nikula <jani.nikula at intel.com>

>
> Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c |   12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 8a66a44..76561e0 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4374,12 +4374,6 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
>  
>  	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
>  
> -	if (!intel_encoder->base.crtc)
> -		return;
> -
> -	if (!to_intel_crtc(intel_encoder->base.crtc)->active)
> -		return;
> -
>  	/* Try to read receiver status if the link appears to be up */
>  	if (!intel_dp_get_link_status(intel_dp, link_status)) {
>  		return;
> @@ -4390,6 +4384,12 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
>  		return;
>  	}
>  
> +	if (!intel_encoder->base.crtc)
> +		return;
> +
> +	if (!to_intel_crtc(intel_encoder->base.crtc)->active)
> +		return;
> +
>  	/* Try to read the source of the interrupt */
>  	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
>  	    intel_dp_get_sink_irq(intel_dp, &sink_irq_vector)) {
> -- 
> 1.7.9.5
>

-- 
Jani Nikula, Intel Open Source Technology Center