[1/1] drm/i915/hdcp: Simplify code in intel_hdcp_auth_downstream()

Message ID 20210527090421.9172-1-thunder.leizhen@huawei.com
State New
Headers show
Series
  • [1/1] drm/i915/hdcp: Simplify code in intel_hdcp_auth_downstream()
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Commit Message

Leizhen (ThunderTown) May 27, 2021, 9:04 a.m.
If intel_hdcp_validate_v_prime() has been successful within the allowed
number of tries, we can directly call drm_dbg_kms() and "goto out" without
jumping out of the loop and repeatedly judging whether the operation is
successful. This can help us reduce an unnecessary if judgment. And it's
a little clearer to read.

No functional change.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>

---
 drivers/gpu/drm/i915/display/intel_hdcp.c | 24 ++++++++++-------------
 1 file changed, 10 insertions(+), 14 deletions(-)

-- 
2.25.1

Comments

Jani Nikula May 27, 2021, 10:04 a.m. | #1
On Thu, 27 May 2021, Zhen Lei <thunder.leizhen@huawei.com> wrote:
> If intel_hdcp_validate_v_prime() has been successful within the allowed

> number of tries, we can directly call drm_dbg_kms() and "goto out" without

> jumping out of the loop and repeatedly judging whether the operation is

> successful. This can help us reduce an unnecessary if judgment. And it's

> a little clearer to read.


Generally I think the "happy day scenario" should be at the topmost
indentation level and not buried in the ifs with a goto exit.

BR,
Jani.

>

> No functional change.

>

> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>

> ---

>  drivers/gpu/drm/i915/display/intel_hdcp.c | 24 ++++++++++-------------

>  1 file changed, 10 insertions(+), 14 deletions(-)

>

> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c

> index d8570e14fe60..c32a854eda66 100644

> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c

> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c

> @@ -663,13 +663,13 @@ int intel_hdcp_auth_downstream(struct intel_connector *connector)

>  

>  	ret = shim->read_ksv_fifo(dig_port, num_downstream, ksv_fifo);

>  	if (ret)

> -		goto err;

> +		goto out;

>  

>  	if (drm_hdcp_check_ksvs_revoked(&dev_priv->drm, ksv_fifo,

>  					num_downstream) > 0) {

>  		drm_err(&dev_priv->drm, "Revoked Ksv(s) in ksv_fifo\n");

>  		ret = -EPERM;

> -		goto err;

> +		goto out;

>  	}

>  

>  	/*

> @@ -680,20 +680,16 @@ int intel_hdcp_auth_downstream(struct intel_connector *connector)

>  		ret = intel_hdcp_validate_v_prime(connector, shim,

>  						  ksv_fifo, num_downstream,

>  						  bstatus);

> -		if (!ret)

> -			break;

> -	}

> -

> -	if (i == tries) {

> -		drm_dbg_kms(&dev_priv->drm,

> -			    "V Prime validation failed.(%d)\n", ret);

> -		goto err;

> +		if (!ret) {

> +			drm_dbg_kms(&dev_priv->drm,

> +				    "HDCP is enabled (%d downstream devices)\n",

> +				    num_downstream);

> +			goto out;

> +		}

>  	}

>  

> -	drm_dbg_kms(&dev_priv->drm, "HDCP is enabled (%d downstream devices)\n",

> -		    num_downstream);

> -	ret = 0;

> -err:

> +	drm_dbg_kms(&dev_priv->drm, "V Prime validation failed.(%d)\n", ret);

> +out:

>  	kfree(ksv_fifo);

>  	return ret;

>  }


-- 
Jani Nikula, Intel Open Source Graphics Center
Leizhen (ThunderTown) May 28, 2021, 9:36 a.m. | #2
On 2021/5/27 18:04, Jani Nikula wrote:
> On Thu, 27 May 2021, Zhen Lei <thunder.leizhen@huawei.com> wrote:

>> If intel_hdcp_validate_v_prime() has been successful within the allowed

>> number of tries, we can directly call drm_dbg_kms() and "goto out" without

>> jumping out of the loop and repeatedly judging whether the operation is

>> successful. This can help us reduce an unnecessary if judgment. And it's

>> a little clearer to read.

> 

> Generally I think the "happy day scenario" should be at the topmost

> indentation level and not buried in the ifs with a goto exit.


for (xxx) {
   if (a == b)
       return found;
}

At least this way of writing is common.


> 

> BR,

> Jani.

> 

>>

>> No functional change.

>>

>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>

>> ---

>>  drivers/gpu/drm/i915/display/intel_hdcp.c | 24 ++++++++++-------------

>>  1 file changed, 10 insertions(+), 14 deletions(-)

>>

>> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c

>> index d8570e14fe60..c32a854eda66 100644

>> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c

>> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c

>> @@ -663,13 +663,13 @@ int intel_hdcp_auth_downstream(struct intel_connector *connector)

>>  

>>  	ret = shim->read_ksv_fifo(dig_port, num_downstream, ksv_fifo);

>>  	if (ret)

>> -		goto err;

>> +		goto out;

>>  

>>  	if (drm_hdcp_check_ksvs_revoked(&dev_priv->drm, ksv_fifo,

>>  					num_downstream) > 0) {

>>  		drm_err(&dev_priv->drm, "Revoked Ksv(s) in ksv_fifo\n");

>>  		ret = -EPERM;

>> -		goto err;

>> +		goto out;

>>  	}

>>  

>>  	/*

>> @@ -680,20 +680,16 @@ int intel_hdcp_auth_downstream(struct intel_connector *connector)

>>  		ret = intel_hdcp_validate_v_prime(connector, shim,

>>  						  ksv_fifo, num_downstream,

>>  						  bstatus);

>> -		if (!ret)

>> -			break;

>> -	}

>> -

>> -	if (i == tries) {

>> -		drm_dbg_kms(&dev_priv->drm,

>> -			    "V Prime validation failed.(%d)\n", ret);

>> -		goto err;

>> +		if (!ret) {

>> +			drm_dbg_kms(&dev_priv->drm,

>> +				    "HDCP is enabled (%d downstream devices)\n",

>> +				    num_downstream);

>> +			goto out;

>> +		}

>>  	}

>>  

>> -	drm_dbg_kms(&dev_priv->drm, "HDCP is enabled (%d downstream devices)\n",

>> -		    num_downstream);

>> -	ret = 0;

>> -err:

>> +	drm_dbg_kms(&dev_priv->drm, "V Prime validation failed.(%d)\n", ret);

>> +out:

>>  	kfree(ksv_fifo);

>>  	return ret;

>>  }

>
Jani Nikula May 31, 2021, 10:36 a.m. | #3
On Fri, 28 May 2021, "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com> wrote:
> On 2021/5/27 18:04, Jani Nikula wrote:

>> On Thu, 27 May 2021, Zhen Lei <thunder.leizhen@huawei.com> wrote:

>>> If intel_hdcp_validate_v_prime() has been successful within the allowed

>>> number of tries, we can directly call drm_dbg_kms() and "goto out" without

>>> jumping out of the loop and repeatedly judging whether the operation is

>>> successful. This can help us reduce an unnecessary if judgment. And it's

>>> a little clearer to read.

>> 

>> Generally I think the "happy day scenario" should be at the topmost

>> indentation level and not buried in the ifs with a goto exit.

>

> for (xxx) {

>    if (a == b)

>        return found;

> }

>

> At least this way of writing is common.


Yes, if the loop is abstracted to a separate function.

BR,
Jani.

>

>

>> 

>> BR,

>> Jani.

>> 

>>>

>>> No functional change.

>>>

>>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>

>>> ---

>>>  drivers/gpu/drm/i915/display/intel_hdcp.c | 24 ++++++++++-------------

>>>  1 file changed, 10 insertions(+), 14 deletions(-)

>>>

>>> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c

>>> index d8570e14fe60..c32a854eda66 100644

>>> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c

>>> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c

>>> @@ -663,13 +663,13 @@ int intel_hdcp_auth_downstream(struct intel_connector *connector)

>>>  

>>>  	ret = shim->read_ksv_fifo(dig_port, num_downstream, ksv_fifo);

>>>  	if (ret)

>>> -		goto err;

>>> +		goto out;

>>>  

>>>  	if (drm_hdcp_check_ksvs_revoked(&dev_priv->drm, ksv_fifo,

>>>  					num_downstream) > 0) {

>>>  		drm_err(&dev_priv->drm, "Revoked Ksv(s) in ksv_fifo\n");

>>>  		ret = -EPERM;

>>> -		goto err;

>>> +		goto out;

>>>  	}

>>>  

>>>  	/*

>>> @@ -680,20 +680,16 @@ int intel_hdcp_auth_downstream(struct intel_connector *connector)

>>>  		ret = intel_hdcp_validate_v_prime(connector, shim,

>>>  						  ksv_fifo, num_downstream,

>>>  						  bstatus);

>>> -		if (!ret)

>>> -			break;

>>> -	}

>>> -

>>> -	if (i == tries) {

>>> -		drm_dbg_kms(&dev_priv->drm,

>>> -			    "V Prime validation failed.(%d)\n", ret);

>>> -		goto err;

>>> +		if (!ret) {

>>> +			drm_dbg_kms(&dev_priv->drm,

>>> +				    "HDCP is enabled (%d downstream devices)\n",

>>> +				    num_downstream);

>>> +			goto out;

>>> +		}

>>>  	}

>>>  

>>> -	drm_dbg_kms(&dev_priv->drm, "HDCP is enabled (%d downstream devices)\n",

>>> -		    num_downstream);

>>> -	ret = 0;

>>> -err:

>>> +	drm_dbg_kms(&dev_priv->drm, "V Prime validation failed.(%d)\n", ret);

>>> +out:

>>>  	kfree(ksv_fifo);

>>>  	return ret;

>>>  }

>> 

>


-- 
Jani Nikula, Intel Open Source Graphics Center

Patch

diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
index d8570e14fe60..c32a854eda66 100644
--- a/drivers/gpu/drm/i915/display/intel_hdcp.c
+++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
@@ -663,13 +663,13 @@  int intel_hdcp_auth_downstream(struct intel_connector *connector)
 
 	ret = shim->read_ksv_fifo(dig_port, num_downstream, ksv_fifo);
 	if (ret)
-		goto err;
+		goto out;
 
 	if (drm_hdcp_check_ksvs_revoked(&dev_priv->drm, ksv_fifo,
 					num_downstream) > 0) {
 		drm_err(&dev_priv->drm, "Revoked Ksv(s) in ksv_fifo\n");
 		ret = -EPERM;
-		goto err;
+		goto out;
 	}
 
 	/*
@@ -680,20 +680,16 @@  int intel_hdcp_auth_downstream(struct intel_connector *connector)
 		ret = intel_hdcp_validate_v_prime(connector, shim,
 						  ksv_fifo, num_downstream,
 						  bstatus);
-		if (!ret)
-			break;
-	}
-
-	if (i == tries) {
-		drm_dbg_kms(&dev_priv->drm,
-			    "V Prime validation failed.(%d)\n", ret);
-		goto err;
+		if (!ret) {
+			drm_dbg_kms(&dev_priv->drm,
+				    "HDCP is enabled (%d downstream devices)\n",
+				    num_downstream);
+			goto out;
+		}
 	}
 
-	drm_dbg_kms(&dev_priv->drm, "HDCP is enabled (%d downstream devices)\n",
-		    num_downstream);
-	ret = 0;
-err:
+	drm_dbg_kms(&dev_priv->drm, "V Prime validation failed.(%d)\n", ret);
+out:
 	kfree(ksv_fifo);
 	return ret;
 }