[Intel-gfx] [PATCH 03/11] drm/i915: Move the DPCD read further up in intel_dp_check_link_status()

[Todd Previte]

Trying again and adding the list this time instead of just replying to 
myself....

This is just an artifact of moving things around, as it likely was in 
the other patches. The only reason I will move comments is to clarify 
what they pertain to if code is moving around it. In any case, it's back 
where it belongs in the updated patch.

-T

On 4/10/15 9:12 AM, Todd Previte wrote:
> Move the DPCD read to the top and check for an interrupt from the sink to catch
> Displayport automated testing requests necessary to support Displayport
> compliance testing. The checks for active connectors and link status are moved
> below the check for the interrupt.
>
> The main reason for doing this is to make sure that a test request isn't missed.
> Checking for the status of the encoder/crtc isn't necessary for some test cases
> (AUX channel tests are one example) and without moving the check for the
> interrupt, these tests may not execute if one of those checks fails.
> Additionally, if reading the DPCD fails, regardless of whether or not testing is
> happening, there's no way to train the link since configurations and status
> can't be read, nor can link training parameters be written.
>
> V1:
> - This is the second part of the single-patch split previously
>    mentioned.
>
> Signed-off-by: Todd Previte <tprevite at gmail.com>
> ---
>   drivers/gpu/drm/i915/intel_dp.c | 15 ++++++++++++++-
>   1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 30cd433..23184b0 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3913,13 +3913,26 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
>   		drm_dp_dpcd_writeb(&intel_dp->aux,
>   				   DP_DEVICE_SERVICE_IRQ_VECTOR,
>   				   sink_irq_vector);
> -
>   		if (sink_irq_vector & DP_AUTOMATED_TEST_REQUEST)
>   			intel_dp_handle_test_request(intel_dp);
>   		if (sink_irq_vector & (DP_CP_IRQ | DP_SINK_SPECIFIC_IRQ))
>   			DRM_DEBUG_DRIVER("CP or sink specific irq unhandled\n");
>   	}
>   
> +	if (!intel_encoder->connectors_active)
> +		return;
> +
> +	if (WARN_ON(!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;
> +	}
> +
>   	if (!drm_dp_channel_eq_ok(link_status, intel_dp->lane_count)) {
>   		DRM_DEBUG_KMS("%s: channel EQ not ok, retraining\n",
>   			      intel_encoder->base.name);