[PATCH] drm/dsi: Fix improper use of mipi_dsi_device_transfer() return value

[PATCH] drm/dsi: Fix improper use of mipi_dsi_device_transfer() return value

[Philippe Cornu]

The function mipi_dsi_device_transfer() returns the number of transmitted
or received bytes on success or a negative error code on failure.

The functions mipi_dsi_shutdown_peripheral(), mipi_dsi_turn_on_peripheral() &
mipi_dsi_set_maximum_return_packet_size() use improperly this returned
value in case of success: 0 should be returned instead of the number of
transmitted bytes.

Signed-off-by: Philippe Cornu <philippe.cornu@st.com>
---
 drivers/gpu/drm/drm_mipi_dsi.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 4b47226b90d4..bc73b7f5b9fc 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -498,8 +498,9 @@ int mipi_dsi_shutdown_peripheral(struct mipi_dsi_device *dsi)
 		.tx_buf = (u8 [2]) { 0, 0 },
 		.tx_len = 2,
 	};
+	int ret = mipi_dsi_device_transfer(dsi, &msg);
 
-	return mipi_dsi_device_transfer(dsi, &msg);
+	return (ret < 0) ? ret : 0;
 }
 EXPORT_SYMBOL(mipi_dsi_shutdown_peripheral);
 
@@ -517,8 +518,9 @@ int mipi_dsi_turn_on_peripheral(struct mipi_dsi_device *dsi)
 		.tx_buf = (u8 [2]) { 0, 0 },
 		.tx_len = 2,
 	};
+	int ret = mipi_dsi_device_transfer(dsi, &msg);
 
-	return mipi_dsi_device_transfer(dsi, &msg);
+	return (ret < 0) ? ret : 0;
 }
 EXPORT_SYMBOL(mipi_dsi_turn_on_peripheral);
 
@@ -541,8 +543,9 @@ int mipi_dsi_set_maximum_return_packet_size(struct mipi_dsi_device *dsi,
 		.tx_len = sizeof(tx),
 		.tx_buf = tx,
 	};
+	int ret = mipi_dsi_device_transfer(dsi, &msg);
 
-	return mipi_dsi_device_transfer(dsi, &msg);
+	return (ret < 0) ? ret : 0;
 }
 EXPORT_SYMBOL(mipi_dsi_set_maximum_return_packet_size);
 
-- 
2.15.1

Re: [PATCH] drm/dsi: Fix improper use of mipi_dsi_device_transfer() return value

[Andrzej Hajda]

On 12.01.2018 15:48, Philippe Cornu wrote:
> The function mipi_dsi_device_transfer() returns the number of transmitted
> or received bytes on success or a negative error code on failure.
>
> The functions mipi_dsi_shutdown_peripheral(), mipi_dsi_turn_on_peripheral() &
> mipi_dsi_set_maximum_return_packet_size() use improperly this returned
> value in case of success: 0 should be returned instead of the number of
> transmitted bytes.
>
> Signed-off-by: Philippe Cornu <philippe.cornu@st.com>

I guess, the best would be to create and use some helper similar to
PTR_ERR_OR_ZERO,
but this is also OK.

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>

 --
Regards
Andrzej

> ---
>  drivers/gpu/drm/drm_mipi_dsi.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> index 4b47226b90d4..bc73b7f5b9fc 100644
> --- a/drivers/gpu/drm/drm_mipi_dsi.c
> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
> @@ -498,8 +498,9 @@ int mipi_dsi_shutdown_peripheral(struct mipi_dsi_device *dsi)
>  		.tx_buf = (u8 [2]) { 0, 0 },
>  		.tx_len = 2,
>  	};
> +	int ret = mipi_dsi_device_transfer(dsi, &msg);
>  
> -	return mipi_dsi_device_transfer(dsi, &msg);
> +	return (ret < 0) ? ret : 0;
>  }
>  EXPORT_SYMBOL(mipi_dsi_shutdown_peripheral);
>  
> @@ -517,8 +518,9 @@ int mipi_dsi_turn_on_peripheral(struct mipi_dsi_device *dsi)
>  		.tx_buf = (u8 [2]) { 0, 0 },
>  		.tx_len = 2,
>  	};
> +	int ret = mipi_dsi_device_transfer(dsi, &msg);
>  
> -	return mipi_dsi_device_transfer(dsi, &msg);
> +	return (ret < 0) ? ret : 0;
>  }
>  EXPORT_SYMBOL(mipi_dsi_turn_on_peripheral);
>  
> @@ -541,8 +543,9 @@ int mipi_dsi_set_maximum_return_packet_size(struct mipi_dsi_device *dsi,
>  		.tx_len = sizeof(tx),
>  		.tx_buf = tx,
>  	};
> +	int ret = mipi_dsi_device_transfer(dsi, &msg);
>  
> -	return mipi_dsi_device_transfer(dsi, &msg);
> +	return (ret < 0) ? ret : 0;
>  }
>  EXPORT_SYMBOL(mipi_dsi_set_maximum_return_packet_size);
>  

Re: [PATCH] drm/dsi: Fix improper use of mipi_dsi_device_transfer() return value

[Philippe CORNU]

Hi Andrzej,

On 01/15/2018 10:12 AM, Andrzej Hajda wrote:
> On 12.01.2018 15:48, Philippe Cornu wrote:
>> The function mipi_dsi_device_transfer() returns the number of transmitted
>> or received bytes on success or a negative error code on failure.
>>
>> The functions mipi_dsi_shutdown_peripheral(), mipi_dsi_turn_on_peripheral() &
>> mipi_dsi_set_maximum_return_packet_size() use improperly this returned
>> value in case of success: 0 should be returned instead of the number of
>> transmitted bytes.
>>
>> Signed-off-by: Philippe Cornu <philippe.cornu@st.com>
> 
> I guess, the best would be to create and use some helper similar to
> PTR_ERR_OR_ZERO,
> but this is also OK.
> 

Many thanks for your comment and review.

Before sending this patch, I searched for a better way to write these 
few lines, including searching for such macros but I did not find 
anything (pointers are largely covered but simple integers are not).

If someone has a better solution (with macros or otherwise), I am happy 
to learn/implement it.

Many thanks,
Philippe : )

> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
> 
>   --
> Regards
> Andrzej
> 
>> ---
>>   drivers/gpu/drm/drm_mipi_dsi.c | 9 ++++++---
>>   1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
>> index 4b47226b90d4..bc73b7f5b9fc 100644
>> --- a/drivers/gpu/drm/drm_mipi_dsi.c
>> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
>> @@ -498,8 +498,9 @@ int mipi_dsi_shutdown_peripheral(struct mipi_dsi_device *dsi)
>>   		.tx_buf = (u8 [2]) { 0, 0 },
>>   		.tx_len = 2,
>>   	};
>> +	int ret = mipi_dsi_device_transfer(dsi, &msg);
>>   
>> -	return mipi_dsi_device_transfer(dsi, &msg);
>> +	return (ret < 0) ? ret : 0;
>>   }
>>   EXPORT_SYMBOL(mipi_dsi_shutdown_peripheral);
>>   
>> @@ -517,8 +518,9 @@ int mipi_dsi_turn_on_peripheral(struct mipi_dsi_device *dsi)
>>   		.tx_buf = (u8 [2]) { 0, 0 },
>>   		.tx_len = 2,
>>   	};
>> +	int ret = mipi_dsi_device_transfer(dsi, &msg);
>>   
>> -	return mipi_dsi_device_transfer(dsi, &msg);
>> +	return (ret < 0) ? ret : 0;
>>   }
>>   EXPORT_SYMBOL(mipi_dsi_turn_on_peripheral);
>>   
>> @@ -541,8 +543,9 @@ int mipi_dsi_set_maximum_return_packet_size(struct mipi_dsi_device *dsi,
>>   		.tx_len = sizeof(tx),
>>   		.tx_buf = tx,
>>   	};
>> +	int ret = mipi_dsi_device_transfer(dsi, &msg);
>>   
>> -	return mipi_dsi_device_transfer(dsi, &msg);
>> +	return (ret < 0) ? ret : 0;
>>   }
>>   EXPORT_SYMBOL(mipi_dsi_set_maximum_return_packet_size);
>>   
> 
> 

Re: [PATCH] drm/dsi: Fix improper use of mipi_dsi_device_transfer() return value

[Sean Paul]

On Mon, Jan 15, 2018 at 10:12:24AM +0100, Andrzej Hajda wrote:
> On 12.01.2018 15:48, Philippe Cornu wrote:
> > The function mipi_dsi_device_transfer() returns the number of transmitted
> > or received bytes on success or a negative error code on failure.
> >
> > The functions mipi_dsi_shutdown_peripheral(), mipi_dsi_turn_on_peripheral() &
> > mipi_dsi_set_maximum_return_packet_size() use improperly this returned
> > value in case of success: 0 should be returned instead of the number of
> > transmitted bytes.
> >
> > Signed-off-by: Philippe Cornu <philippe.cornu@st.com>
> 
> I guess, the best would be to create and use some helper similar to
> PTR_ERR_OR_ZERO,
> but this is also OK.
> 
> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>

Applied to drm-misc-next. Thanks for the patch and review

Sean

> 
>  --
> Regards
> Andrzej
> 
> > ---
> >  drivers/gpu/drm/drm_mipi_dsi.c | 9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> > index 4b47226b90d4..bc73b7f5b9fc 100644
> > --- a/drivers/gpu/drm/drm_mipi_dsi.c
> > +++ b/drivers/gpu/drm/drm_mipi_dsi.c
> > @@ -498,8 +498,9 @@ int mipi_dsi_shutdown_peripheral(struct mipi_dsi_device *dsi)
> >  		.tx_buf = (u8 [2]) { 0, 0 },
> >  		.tx_len = 2,
> >  	};
> > +	int ret = mipi_dsi_device_transfer(dsi, &msg);
> >  
> > -	return mipi_dsi_device_transfer(dsi, &msg);
> > +	return (ret < 0) ? ret : 0;
> >  }
> >  EXPORT_SYMBOL(mipi_dsi_shutdown_peripheral);
> >  
> > @@ -517,8 +518,9 @@ int mipi_dsi_turn_on_peripheral(struct mipi_dsi_device *dsi)
> >  		.tx_buf = (u8 [2]) { 0, 0 },
> >  		.tx_len = 2,
> >  	};
> > +	int ret = mipi_dsi_device_transfer(dsi, &msg);
> >  
> > -	return mipi_dsi_device_transfer(dsi, &msg);
> > +	return (ret < 0) ? ret : 0;
> >  }
> >  EXPORT_SYMBOL(mipi_dsi_turn_on_peripheral);
> >  
> > @@ -541,8 +543,9 @@ int mipi_dsi_set_maximum_return_packet_size(struct mipi_dsi_device *dsi,
> >  		.tx_len = sizeof(tx),
> >  		.tx_buf = tx,
> >  	};
> > +	int ret = mipi_dsi_device_transfer(dsi, &msg);
> >  
> > -	return mipi_dsi_device_transfer(dsi, &msg);
> > +	return (ret < 0) ? ret : 0;
> >  }
> >  EXPORT_SYMBOL(mipi_dsi_set_maximum_return_packet_size);
> >  
> 
> 

-- 
Sean Paul, Software Engineer, Google / Chromium OS