lkml.org 
[lkml]   [2022]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v2 3/7] tty: serial: samsung: constify s3c24xx_serial_drv_data
From
On 07/03/2022 09:33, Jiri Slaby wrote:
> On 07. 03. 22, 9:09, Krzysztof Kozlowski wrote:
>> The driver data (struct s3c24xx_serial_drv_data) is only used to
>> initialize the driver properly and is not modified. Make it const.
> ...
>> @@ -2755,9 +2755,9 @@ static struct s3c24xx_serial_drv_data s5pv210_serial_drv_data = {
>> },
>> .fifosize = { 256, 64, 16, 16 },
>> };
>> -#define S5PV210_SERIAL_DRV_DATA ((kernel_ulong_t)&s5pv210_serial_drv_data)
>> +#define S5PV210_SERIAL_DRV_DATA (&s5pv210_serial_drv_data)
>> #else
>> -#define S5PV210_SERIAL_DRV_DATA (kernel_ulong_t)NULL
>> +#define S5PV210_SERIAL_DRV_DATA NULL
>
> Yet, I still don't see why the switch from ulong->ptr happens in this
> "constify it" patch?

All these defines S5PV210_SERIAL_DRV_DATA and so on are now const and
are assigned to of_device_id.data (s3c24xx_uart_dt_match). Before, these
were assigned with a cast:

static const struct of_device_id s3c24xx_uart_dt_match[] = {
{ .compatible = "samsung,s5pv210-uart",

.data = (void *)S5PV210_SERIAL_DRV_DATA }

but since the actual data structure is const, I want to drop the cast.
Casting const via (void *) might hide some possible issues, e.g. if
of_device_id.data becomes actually non-const. There is no particular
issue here, because of_device_id.data and S5PV210_SERIAL_DRV_DATA are
const. But also because they are both const now, I want to drop the cast
via void *.

When (void *) is dropped, the S5PV210_SERIAL_DRV_DATA cannot be
kernel_ulong_t:

../drivers/tty/serial/samsung_tty.c:2753:33: warning: initialization of
‘const void *’ from ‘long unsigned int’ makes pointer from integer
without a cast [-Wint-conversion]

2753 | #define S5PV210_SERIAL_DRV_DATA (kernel_ulong_t)NULL



Best regards,
Krzysztof

\
 
 \ /
  Last update: 2022-03-07 09:41    [W:0.050 / U:0.820 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site