[PATCH] clk: clk-divider: fix divisor > 255 bug

[PATCH] clk: clk-divider: fix divisor > 255 bug

[James Hogan]

Commit 6d9252bd9a4bb (clk: Add support for power of two type dividers)
merged in v3.6 added the _get_val function to convert a divisor value to
a register field value depending on the flags. However it used the type
u8 for the div field, causing divisors larger than 255 to be masked
and the resultant clock rate to be too high.

E.g. in my case an 11bit divider was supposed to divide 24.576 MHz down
to 32.768KHz. The divisor was correctly calculated as 750 (0x2ee). This
was masked to 238 (0xee) resulting in a frequency of 103.26KHz.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: linux-arm-kernel at lists.infradead.org
Cc: stable at vger.kernel.org
---
Since this bug was introduced in 3.6, it probably should by applied to
stable 3.10 and 3.12.
---
 drivers/clk/clk-divider.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index 8d3009e44fba..5543b7df8e16 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c
@@ -87,7 +87,7 @@ static unsigned int _get_table_val(const struct clk_div_table *table,
 	return 0;
 }
 
-static unsigned int _get_val(struct clk_divider *divider, u8 div)
+static unsigned int _get_val(struct clk_divider *divider, unsigned int div)
 {
 	if (divider->flags & CLK_DIVIDER_ONE_BASED)
 		return div;
-- 
1.8.1.2

[PATCH] clk: clk-divider: fix divisor > 255 bug

[Mike Turquette]

Quoting James Hogan (2013-12-16 02:41:38)
> Commit 6d9252bd9a4bb (clk: Add support for power of two type dividers)
> merged in v3.6 added the _get_val function to convert a divisor value to
> a register field value depending on the flags. However it used the type
> u8 for the div field, causing divisors larger than 255 to be masked
> and the resultant clock rate to be too high.
> 
> E.g. in my case an 11bit divider was supposed to divide 24.576 MHz down
> to 32.768KHz. The divisor was correctly calculated as 750 (0x2ee). This
> was masked to 238 (0xee) resulting in a frequency of 103.26KHz.
> 
> Signed-off-by: James Hogan <james.hogan@imgtec.com>

Taken into clk-next. Thanks for the fix!

Regards,
Mike

> Cc: Rajendra Nayak <rnayak@ti.com>
> Cc: Mike Turquette <mturquette@linaro.org>
> Cc: linux-arm-kernel at lists.infradead.org
> Cc: stable at vger.kernel.org
> ---
> Since this bug was introduced in 3.6, it probably should by applied to
> stable 3.10 and 3.12.
> ---
>  drivers/clk/clk-divider.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> index 8d3009e44fba..5543b7df8e16 100644
> --- a/drivers/clk/clk-divider.c
> +++ b/drivers/clk/clk-divider.c
> @@ -87,7 +87,7 @@ static unsigned int _get_table_val(const struct clk_div_table *table,
>         return 0;
>  }
>  
> -static unsigned int _get_val(struct clk_divider *divider, u8 div)
> +static unsigned int _get_val(struct clk_divider *divider, unsigned int div)
>  {
>         if (divider->flags & CLK_DIVIDER_ONE_BASED)
>                 return div;
> -- 
> 1.8.1.2
> 
> 

[PATCH] clk: clk-divider: fix divisor > 255 bug

[James Hogan]

On 03/01/14 04:15, Mike Turquette wrote:
> Quoting James Hogan (2013-12-16 02:41:38)
>> Commit 6d9252bd9a4bb (clk: Add support for power of two type dividers)
>> merged in v3.6 added the _get_val function to convert a divisor value to
>> a register field value depending on the flags. However it used the type
>> u8 for the div field, causing divisors larger than 255 to be masked
>> and the resultant clock rate to be too high.
>>
>> E.g. in my case an 11bit divider was supposed to divide 24.576 MHz down
>> to 32.768KHz. The divisor was correctly calculated as 750 (0x2ee). This
>> was masked to 238 (0xee) resulting in a frequency of 103.26KHz.
>>
>> Signed-off-by: James Hogan <james.hogan@imgtec.com>
> 
> Taken into clk-next. Thanks for the fix!

Thanks Mike, is there any chance of getting this into v3.13, or is it
too late?

Cheers
James

>> Cc: Rajendra Nayak <rnayak@ti.com>
>> Cc: Mike Turquette <mturquette@linaro.org>
>> Cc: linux-arm-kernel at lists.infradead.org
>> Cc: stable at vger.kernel.org
>> ---
>> Since this bug was introduced in 3.6, it probably should by applied to
>> stable 3.10 and 3.12.
>> ---
>>  drivers/clk/clk-divider.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
>> index 8d3009e44fba..5543b7df8e16 100644
>> --- a/drivers/clk/clk-divider.c
>> +++ b/drivers/clk/clk-divider.c
>> @@ -87,7 +87,7 @@ static unsigned int _get_table_val(const struct clk_div_table *table,
>>         return 0;
>>  }
>>  
>> -static unsigned int _get_val(struct clk_divider *divider, u8 div)
>> +static unsigned int _get_val(struct clk_divider *divider, unsigned int div)
>>  {
>>         if (divider->flags & CLK_DIVIDER_ONE_BASED)
>>                 return div;
>> -- 
>> 1.8.1.2
>>
>>

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[PATCH] clk: clk-divider: fix divisor > 255 bug

[Mike Turquette]

Quoting James Hogan (2014-01-06 02:07:58)
> On 03/01/14 04:15, Mike Turquette wrote:
> > Quoting James Hogan (2013-12-16 02:41:38)
> >> Commit 6d9252bd9a4bb (clk: Add support for power of two type dividers)
> >> merged in v3.6 added the _get_val function to convert a divisor value to
> >> a register field value depending on the flags. However it used the type
> >> u8 for the div field, causing divisors larger than 255 to be masked
> >> and the resultant clock rate to be too high.
> >>
> >> E.g. in my case an 11bit divider was supposed to divide 24.576 MHz down
> >> to 32.768KHz. The divisor was correctly calculated as 750 (0x2ee). This
> >> was masked to 238 (0xee) resulting in a frequency of 103.26KHz.
> >>
> >> Signed-off-by: James Hogan <james.hogan@imgtec.com>
> > 
> > Taken into clk-next. Thanks for the fix!
> 
> Thanks Mike, is there any chance of getting this into v3.13, or is it
> too late?

I had applied it to clk-next but I just moved it over to my -fixes
branch. Will send later today.

Regards,
Mike

> 
> Cheers
> James
> 
> >> Cc: Rajendra Nayak <rnayak@ti.com>
> >> Cc: Mike Turquette <mturquette@linaro.org>
> >> Cc: linux-arm-kernel at lists.infradead.org
> >> Cc: stable at vger.kernel.org
> >> ---
> >> Since this bug was introduced in 3.6, it probably should by applied to
> >> stable 3.10 and 3.12.
> >> ---
> >>  drivers/clk/clk-divider.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> >> index 8d3009e44fba..5543b7df8e16 100644
> >> --- a/drivers/clk/clk-divider.c
> >> +++ b/drivers/clk/clk-divider.c
> >> @@ -87,7 +87,7 @@ static unsigned int _get_table_val(const struct clk_div_table *table,
> >>         return 0;
> >>  }
> >>  
> >> -static unsigned int _get_val(struct clk_divider *divider, u8 div)
> >> +static unsigned int _get_val(struct clk_divider *divider, unsigned int div)
> >>  {
> >>         if (divider->flags & CLK_DIVIDER_ONE_BASED)
> >>                 return div;
> >> -- 
> >> 1.8.1.2
> >>
> >>
>