linux-kernel - Re: [PATCH 2/2] drm/i915/dp: Use common error handling code in intel_dp_sink_crc

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Date:   Tue, 24 Oct 2017 19:13:27 +0300
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     SF Markus Elfring <elfring@...rs.sourceforge.net>,
        dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
        David Airlie <airlied@...ux.ie>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 2/2] drm/i915/dp: Use common error handling code in intel_dp_sink_crc_stop()

On Tue, 24 Oct 2017, SF Markus Elfring <elfring@...rs.sourceforge.net> wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Tue, 24 Oct 2017 15:40:47 +0200
>
> Adjust jump targets so that a specific error code assignment
> will be in the implementation only at the end of this function.

This is not an issue that needs to be "fixed".

>
> This issue was detected by using the Coccinelle software.
>
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 30 ++++++++++++++----------------
>  1 file changed, 14 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 342f1a1fa085..3dd514a77008 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3894,27 +3894,19 @@ static int intel_dp_sink_crc_stop(struct intel_dp *intel_dp)
>  	int count = 0;
>  	int attempts = 10;
>  
> -	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK, &buf) < 0) {
> -		DRM_DEBUG_KMS("Sink CRC couldn't be stopped properly\n");
> -		ret = -EIO;
> -		goto out;
> -	}
> +	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK, &buf) < 0)
> +		goto report_failure;
>  
>  	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_TEST_SINK,
> -			       buf & ~DP_TEST_SINK_START) < 0) {
> -		DRM_DEBUG_KMS("Sink CRC couldn't be stopped properly\n");
> -		ret = -EIO;
> -		goto out;

I'd rather change the debug messages to distinguish the cases. I also
want to keep ret = -EIO in each individual branch, to distinguish from
the cases where it's set to something other than -EIO.

> -	}
> +			       buf & ~DP_TEST_SINK_START) < 0)
> +		goto report_failure;
>  
>  	do {
>  		intel_wait_for_vblank(dev_priv, intel_crtc->pipe);
> +		if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK_MISC, &buf)
> +		    < 0)
> +			goto e_io;
>  
> -		if (drm_dp_dpcd_readb(&intel_dp->aux,
> -				      DP_TEST_SINK_MISC, &buf) < 0) {
> -			ret = -EIO;
> -			goto out;
> -		}

This is good as it is. The change makes it worse.

>  		count = buf & DP_TEST_COUNT_MASK;
>  	} while (--attempts && count);
>  
> @@ -3923,9 +3915,15 @@ static int intel_dp_sink_crc_stop(struct intel_dp *intel_dp)
>  		ret = -ETIMEDOUT;
>  	}
>  
> - out:
> +enable_ips:
>  	hsw_enable_ips(intel_crtc);
>  	return ret;
> +
> +report_failure:
> +	DRM_DEBUG_KMS("Sink CRC couldn't be stopped properly\n");
> +e_io:
> +	ret = -EIO;
> +	goto enable_ips;

*shudder* Please no.

BR,
Jani.

>  }
>  
>  static int intel_dp_sink_crc_start(struct intel_dp *intel_dp)

-- 
Jani Nikula, Intel Open Source Technology Center