Re: [PATCH 1/4] drm/i915: Avoid EBUSY retry on intel_dp_aux_ch.

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Oct 21, 2015 at 10:28:51AM -0700, Rodrigo Vivi wrote:
> EBUSY retries are already in place at drm level.
> We don't need to replicate the job here.
> 
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 20 ++------------------
>  1 file changed, 2 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 09bdd94..d054129 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -818,24 +818,8 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
>  
>  	intel_aux_display_runtime_get(dev_priv);
>  
> -	/* Try to wait for any previous AUX channel activity */
> -	for (try = 0; try < 3; try++) {
> -		status = I915_READ_NOTRACE(ch_ctl);
> -		if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0)
> -			break;
> -		msleep(1);

The dp helper doesn't sleep at all between the retries, so dropping the
sleep from here may change the behaviour.

> -	}
> -
> -	if (try == 3) {
> -		static u32 last_status = -1;
> -		const u32 status = I915_READ(ch_ctl);
> -
> -		if (status != last_status) {
> -			WARN(1, "dp_aux_ch not started status 0x%08x\n",
> -			     status);
> -			last_status = status;
> -		}
> -
> +	status = I915_READ_NOTRACE(ch_ctl);
> +	if ((status & DP_AUX_CH_CTL_SEND_BUSY) != 0) {
>  		ret = -EBUSY;
>  		goto out;
>  	}
> -- 
> 2.4.3
> 
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-- 
Ville Syrjälä
Intel OTC
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