[PATCH] gpio: altera-a10sr: constify gpio_chip structure

[PATCH] gpio: altera-a10sr: constify gpio_chip structure

[Gustavo A. R. Silva]

This structure is only used to copy into another structure, so declare
it as const.

This issue was detected using Coccinelle and the following semantic patch:

@r disable optional_qualifier@
identifier i;
position p;
@@
static struct gpio_chip i@p = { ... };

@ok@
identifier r.i;
expression e;
position p;
@@
e = i@p;

@bad@
position p != {r.p,ok.p};
identifier r.i;
struct gpio_chip e;
@@
e@i@p

@depends on !bad disable optional_qualifier@
identifier r.i;
@@
static
+const
 struct gpio_chip i = { ... };

In the following log you can see a significant difference in the code size
and data segment, hence in the dec segment. This log is the output
of the size command, before and after the code change:

before:
   text    data     bss     dec     hex filename
   1954     600       0    2554     9fa drivers/gpio/gpio-altera-a10sr.o

after:
   text    data     bss     dec     hex filename
   1655     512       0    2167     877 drivers/gpio/gpio-altera-a10sr.o

Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
---
 drivers/gpio/gpio-altera-a10sr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-altera-a10sr.c b/drivers/gpio/gpio-altera-a10sr.c
index 16a8951..6b11f13 100644
--- a/drivers/gpio/gpio-altera-a10sr.c
+++ b/drivers/gpio/gpio-altera-a10sr.c
@@ -71,7 +71,7 @@ static int altr_a10sr_gpio_direction_output(struct gpio_chip *gc,
 	return -EINVAL;
 }
 
-static struct gpio_chip altr_a10sr_gc = {
+static const struct gpio_chip altr_a10sr_gc = {
 	.label = "altr_a10sr_gpio",
 	.owner = THIS_MODULE,
 	.get = altr_a10sr_gpio_get,
-- 
2.5.0

Re: [PATCH] gpio: altera-a10sr: constify gpio_chip structure

[Thor Thayer]

On 07/11/2017 05:15 PM, Gustavo A. R. Silva wrote:
> This structure is only used to copy into another structure, so declare
> it as const.

<snip>

> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
> ---
>   drivers/gpio/gpio-altera-a10sr.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpio/gpio-altera-a10sr.c b/drivers/gpio/gpio-altera-a10sr.c
> index 16a8951..6b11f13 100644
> --- a/drivers/gpio/gpio-altera-a10sr.c
> +++ b/drivers/gpio/gpio-altera-a10sr.c
> @@ -71,7 +71,7 @@ static int altr_a10sr_gpio_direction_output(struct gpio_chip *gc,
>   	return -EINVAL;
>   }
>   
> -static struct gpio_chip altr_a10sr_gc = {
> +static const struct gpio_chip altr_a10sr_gc = {
>   	.label = "altr_a10sr_gpio",
>   	.owner = THIS_MODULE,
>   	.get = altr_a10sr_gpio_get,
> 
Reviewed-by: Thor Thayer <thor.thayer@linux.intel.com>

Re: [PATCH] gpio: altera-a10sr: constify gpio_chip structure

[Gustavo A. R. Silva]

On 07/13/2017 12:41 PM, Thor Thayer wrote:
> On 07/11/2017 05:15 PM, Gustavo A. R. Silva wrote:
>> This structure is only used to copy into another structure, so declare
>> it as const.
>
> <snip>
>
>> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
>> ---
>>   drivers/gpio/gpio-altera-a10sr.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpio/gpio-altera-a10sr.c 
>> b/drivers/gpio/gpio-altera-a10sr.c
>> index 16a8951..6b11f13 100644
>> --- a/drivers/gpio/gpio-altera-a10sr.c
>> +++ b/drivers/gpio/gpio-altera-a10sr.c
>> @@ -71,7 +71,7 @@ static int altr_a10sr_gpio_direction_output(struct 
>> gpio_chip *gc,
>>       return -EINVAL;
>>   }
>>   -static struct gpio_chip altr_a10sr_gc = {
>> +static const struct gpio_chip altr_a10sr_gc = {
>>       .label = "altr_a10sr_gpio",
>>       .owner = THIS_MODULE,
>>       .get = altr_a10sr_gpio_get,
>>
> Reviewed-by: Thor Thayer <thor.thayer@linux.intel.com>

Thank you, Thor.

-- 
Gustavo A. R. Silva

Re: [PATCH] gpio: altera-a10sr: constify gpio_chip structure

[Linus Walleij]

On Wed, Jul 12, 2017 at 12:15 AM, Gustavo A. R. Silva
<garsilva@embeddedor.com> wrote:

> This structure is only used to copy into another structure, so declare
> it as const.
>
> This issue was detected using Coccinelle and the following semantic patch:
>
> @r disable optional_qualifier@
> identifier i;
> position p;
> @@
> static struct gpio_chip i@p = { ... };
>
> @ok@
> identifier r.i;
> expression e;
> position p;
> @@
> e = i@p;
>
> @bad@
> position p != {r.p,ok.p};
> identifier r.i;
> struct gpio_chip e;
> @@
> e@i@p
>
> @depends on !bad disable optional_qualifier@
> identifier r.i;
> @@
> static
> +const
>  struct gpio_chip i = { ... };
>
> In the following log you can see a significant difference in the code size
> and data segment, hence in the dec segment. This log is the output
> of the size command, before and after the code change:
>
> before:
>    text    data     bss     dec     hex filename
>    1954     600       0    2554     9fa drivers/gpio/gpio-altera-a10sr.o
>
> after:
>    text    data     bss     dec     hex filename
>    1655     512       0    2167     877 drivers/gpio/gpio-altera-a10sr.o
>
> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>

Patch applied with Thor's review tag.

Yours,
Linus Walleij