[Intel-gfx] [PATCH 3/8] drm/i915: Use EAGAIN instead EBUSY for aux retry.

[Daniel Vetter]

On Fri, Nov 20, 2015 at 04:46:25PM -0800, Rodrigo Vivi wrote:
> Current EBUSY meaning is immediately retry, but this is
> about to change. DRM aux transfer is about to change and
> make EAGAIN the immediately retry and use EBUSY to wait
> a bit for aux channels to recover for any error or wake up.
> 
> This has no functional change if the EAGAIN support is in
> place already for drm aux transfer.
> 
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

Please document the EAGAIN and EBUSY return codes for the ->transfer
member fo drm_dp_aux in the kerneldoc properly. While at it would be great
if you could document any other error codes that are treated specially for
this function.

Since this will be a bit more text please convert the kerneldoc to the new
per-member comment layout that 4.4 supports, i.e.

/**
 * struct foo - foo structure
 *
 * top-level blabla
 */
struct foo {
	/**
	 * @bar:
	 *
	 * Long text (with paragraphs) explaining bar.
	 */
};

Otherwise this looks really tidy and I really like how this allows us to
get rid of the intel_read_wake hack.
-Daniel

> ---
>  drivers/gpu/drm/i915/intel_dp.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index bec443a..ed07f0a 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -835,7 +835,7 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
>  			last_status = status;
>  		}
>  
> -		ret = -EBUSY;
> +		ret = -EAGAIN;
>  		goto out;
>  	}
>  
> @@ -890,7 +890,7 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
>  
>  	if ((status & DP_AUX_CH_CTL_DONE) == 0) {
>  		DRM_ERROR("dp_aux_ch not done status 0x%08x\n", status);
> -		ret = -EBUSY;
> +		ret = -EAGAIN;
>  		goto out;
>  	}
>  
> -- 
> 2.4.3
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch