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

From: [email-masked] (James Hogan)
Date: Mon, 6 Jan 2014 10:07:58 +0000

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 <[email-masked]>
> 
> 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 <[email-masked]>
>> Cc: Mike Turquette <[email-masked]>
>> 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
>>
>>

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 836 bytes
Desc: OpenPGP digital signature
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20140106/47f6d479/attachment.sig>