[Intel-gfx] [PATCH 1/8] drm/i915/dp: retry link status read 3 times on failure

[Keith Packard]

On Fri,  1 Jul 2011 15:22:51 -0700, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:

> Especially after a hotplug or power status change, the sink may not
> reply immediately to a link status query.  So retry 3 times per the spec
> to really make sure nothing is there.

There's no 'false' return path here. I think you want:
> 
> ---
>  drivers/gpu/drm/i915/intel_dp.c |   17 +++++++++++++----
>  1 files changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 391b55f..1829ecc 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1019,13 +1019,22 @@ intel_dp_dpms(struct drm_encoder *encoder, int mode)
>  static bool
>  intel_dp_get_link_status(struct intel_dp *intel_dp)
>  {
> -	int ret;
> +	int ret, i;
> +
> +	/* Must try AUX reads for this at least 3 times */
> +	for (i = 0; i < 3; i++) {
> +		ret = intel_dp_aux_native_read(intel_dp,
> +					       DP_LANE0_1_STATUS,
> +					       intel_dp->link_status,
> +					       DP_LINK_STATUS_SIZE);
> +		if (ret == DP_LINK_STATUS_SIZE)
> +			break;

                        return true;
> +		msleep(1);
> +	}
>  
> -	ret = intel_dp_aux_native_read(intel_dp,
> -				       DP_LANE0_1_STATUS,
> -				       intel_dp->link_status, DP_LINK_STATUS_SIZE);
>  	if (ret != DP_LINK_STATUS_SIZE)
>  		return false;
> +
>  	return true;

        return false;
        
>  }

-- 
keith.packard at intel.com
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