[PATCH 0/2] GPU-DRM-i915-DP: Fine-tuning for two function implementations

[PATCH 0/2] GPU-DRM-i915-DP: Fine-tuning for two function implementations

[SF Markus Elfring]

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Tue, 24 Oct 2017 15:54:32 +0200

Two update suggestions were taken into account
from static source code analysis.

Markus Elfring (2):
  Delete an unnecessary goto statement in intel_dp_sink_crc()
  Use common error handling code in intel_dp_sink_crc_stop()

 drivers/gpu/drm/i915/intel_dp.c | 34 +++++++++++++++-------------------
 1 file changed, 15 insertions(+), 19 deletions(-)

-- 
2.14.3

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[PATCH 1/2] drm/i915/dp: Delete an unnecessary goto statement in intel_dp_sink_crc()

[SF Markus Elfring]

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Tue, 24 Oct 2017 15:15:20 +0200

A jump was specified for a location which was directly behind.
Thus remove such an unnecessary goto statement.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 drivers/gpu/drm/i915/intel_dp.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index ca48bce23a6f..342f1a1fa085 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3994,10 +3994,8 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
 		goto stop;
 	}
 
-	if (drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_CRC_R_CR, crc, 6) < 0) {
+	if (drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_CRC_R_CR, crc, 6) < 0)
 		ret = -EIO;
-		goto stop;
-	}
 
 stop:
 	intel_dp_sink_crc_stop(intel_dp);
-- 
2.14.3

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[PATCH 2/2] drm/i915/dp: Use common error handling code in intel_dp_sink_crc_stop()

[SF Markus Elfring]

From: Markus Elfring <elfring@users.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 issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.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;
-	}
+			       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;
-		}
 		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;
 }
 
 static int intel_dp_sink_crc_start(struct intel_dp *intel_dp)
-- 
2.14.3

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Re: [PATCH 2/2] drm/i915/dp: Use common error handling code in intel_dp_sink_crc_stop()

[Jani Nikula]

On Tue, 24 Oct 2017, SF Markus Elfring <elfring@users.sourceforge.net> wrote:
> From: Markus Elfring <elfring@users.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@users.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
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