[PATCH 1/1] media: tc358746: Address compiler warnings

[PATCH 1/1] media: tc358746: Address compiler warnings

[Sakari Ailus]

Address these compiler warnings by initialising the m_best and p_best
values to 0 and 1 respectively (as latter is used as a divisor):

   drivers/media/i2c/tc358746.c: In function 'tc358746_find_pll_settings':
>> drivers/media/i2c/tc358746.c:817:13: warning: 'p_best' is used uninitialized
[-Wuninitialized]
     817 |         u16 p_best, p;
         |             ^~~~~~
>> drivers/media/i2c/tc358746.c:816:13: warning: 'm_best' is used uninitialized
[-Wuninitialized]
     816 |         u16 m_best, mul;
         |             ^~~~~~

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202305301627.fLT3Bkds-lkp@intel.com/
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/i2c/tc358746.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/i2c/tc358746.c b/drivers/media/i2c/tc358746.c
index ec1a193ba161a..25fbce5cabdaa 100644
--- a/drivers/media/i2c/tc358746.c
+++ b/drivers/media/i2c/tc358746.c
@@ -813,8 +813,8 @@ static unsigned long tc358746_find_pll_settings(struct tc358746 *tc358746,
 	u32 min_delta = 0xffffffff;
 	u16 prediv_max = 17;
 	u16 prediv_min = 1;
-	u16 m_best, mul;
-	u16 p_best, p;
+	u16 m_best = 0, mul;
+	u16 p_best = 1, p;
 	u8 postdiv;
 
 	if (fout > 1000 * HZ_PER_MHZ) {
-- 
2.30.2

Re: [PATCH 1/1] media: tc358746: Address compiler warnings

[Marco Felsch]

Hi Sakari,

Hans already sent a patch a few months ago:
 - https://lore.kernel.org/linux-media/15030a07-3615-fca0-1891-a234dc054b00@xs4all.nl/

It turned out that the compiler had a bug albeit the compiler listed in
'Closes:' is already a gcc-12 and now the warning used is slightly
different.

I'm not again the patch but we should point out that this patch is only
required to make the compiler happy.

Regards,
  Marco

On 23-05-30, Sakari Ailus wrote:
> Address these compiler warnings by initialising the m_best and p_best
> values to 0 and 1 respectively (as latter is used as a divisor):
> 
>    drivers/media/i2c/tc358746.c: In function 'tc358746_find_pll_settings':
> >> drivers/media/i2c/tc358746.c:817:13: warning: 'p_best' is used uninitialized
> [-Wuninitialized]
>      817 |         u16 p_best, p;
>          |             ^~~~~~
> >> drivers/media/i2c/tc358746.c:816:13: warning: 'm_best' is used uninitialized
> [-Wuninitialized]
>      816 |         u16 m_best, mul;
>          |             ^~~~~~
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202305301627.fLT3Bkds-lkp@intel.com/
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  drivers/media/i2c/tc358746.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/i2c/tc358746.c b/drivers/media/i2c/tc358746.c
> index ec1a193ba161a..25fbce5cabdaa 100644
> --- a/drivers/media/i2c/tc358746.c
> +++ b/drivers/media/i2c/tc358746.c
> @@ -813,8 +813,8 @@ static unsigned long tc358746_find_pll_settings(struct tc358746 *tc358746,
>  	u32 min_delta = 0xffffffff;
>  	u16 prediv_max = 17;
>  	u16 prediv_min = 1;
> -	u16 m_best, mul;
> -	u16 p_best, p;
> +	u16 m_best = 0, mul;
> +	u16 p_best = 1, p;
>  	u8 postdiv;
>  
>  	if (fout > 1000 * HZ_PER_MHZ) {
> -- 
> 2.30.2
> 
> 

Re: [PATCH 1/1] media: tc358746: Address compiler warnings

[Sakari Ailus]

Hi Marco,

On Wed, May 31, 2023 at 10:18:10AM +0200, Marco Felsch wrote:
> Hi Sakari,
> 
> Hans already sent a patch a few months ago:
>  - https://lore.kernel.org/linux-media/15030a07-3615-fca0-1891-a234dc054b00@xs4all.nl/
> 
> It turned out that the compiler had a bug albeit the compiler listed in
> 'Closes:' is already a gcc-12 and now the warning used is slightly
> different.
> 
> I'm not again the patch but we should point out that this patch is only
> required to make the compiler happy.

Ack, thanks. I'll drop this then. The condition isn't trivial for a
compiler to figure out though, even I'm not quite sure this is the case for
all parameter values.

-- 
Kind regards,

Sakari Ailus

Re: [PATCH 1/1] media: tc358746: Address compiler warnings

[Sakari Ailus]

On Thu, Jun 01, 2023 at 08:20:06AM +0000, Sakari Ailus wrote:
> Hi Marco,
> 
> On Wed, May 31, 2023 at 10:18:10AM +0200, Marco Felsch wrote:
> > Hi Sakari,
> > 
> > Hans already sent a patch a few months ago:
> >  - https://lore.kernel.org/linux-media/15030a07-3615-fca0-1891-a234dc054b00@xs4all.nl/
> > 
> > It turned out that the compiler had a bug albeit the compiler listed in
> > 'Closes:' is already a gcc-12 and now the warning used is slightly
> > different.
> > 
> > I'm not again the patch but we should point out that this patch is only
> > required to make the compiler happy.
> 
> Ack, thanks. I'll drop this then. The condition isn't trivial for a
> compiler to figure out though, even I'm not quite sure this is the case for
> all parameter values.

Hans's patch actually assigns p_best to 0 which isn't a best default value
for a divisor.

-- 
Sakari Ailus

Re: [PATCH 1/1] media: tc358746: Address compiler warnings

[Marco Felsch]

Hi Sakari,

On 23-06-01, Sakari Ailus wrote:
> On Thu, Jun 01, 2023 at 08:20:06AM +0000, Sakari Ailus wrote:
> > Hi Marco,
> > 
> > On Wed, May 31, 2023 at 10:18:10AM +0200, Marco Felsch wrote:
> > > Hi Sakari,
> > > 
> > > Hans already sent a patch a few months ago:
> > >  - https://lore.kernel.org/linux-media/15030a07-3615-fca0-1891-a234dc054b00@xs4all.nl/
> > > 
> > > It turned out that the compiler had a bug albeit the compiler listed in
> > > 'Closes:' is already a gcc-12 and now the warning used is slightly
> > > different.
> > > 
> > > I'm not again the patch but we should point out that this patch is only
> > > required to make the compiler happy.
> > 
> > Ack, thanks. I'll drop this then. The condition isn't trivial for a
> > compiler to figure out though, even I'm not quite sure this is the case for
> > all parameter values.

I don't want to complain here O:) and as I said we can pick the patch
but we should mention that this is a patch for the compiler.

> Hans's patch actually assigns p_best to 0 which isn't a best default value
> for a divisor.

You're right.

Regards,
  Marco