[PATCH 1/7] wdt: dw: Switch to using fls for log2

[Sean Anderson]

On 8/5/20 5:06 PM, Heinrich Schuchardt wrote:
> On 8/5/20 9:14 PM, Sean Anderson wrote:
>> log_2_n_round_up is only found in arm. fls performs the same job and is
>> generic.
>>
>> Signed-off-by: Sean Anderson <seanga2 at gmail.com>
>> ---
>>
>>  drivers/watchdog/designware_wdt.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/watchdog/designware_wdt.c b/drivers/watchdog/designware_wdt.c
>> index 12f09a7a39..5684acefd2 100644
>> --- a/drivers/watchdog/designware_wdt.c
>> +++ b/drivers/watchdog/designware_wdt.c
>> @@ -9,7 +9,6 @@
>>  #include <reset.h>
>>  #include <wdt.h>
>>  #include <asm/io.h>
>> -#include <asm/utils.h>
>>  #include <linux/bitops.h>
>>
>>  #define DW_WDT_CR	0x00
>> @@ -35,7 +34,7 @@ static int designware_wdt_settimeout(void __iomem *base, unsigned int clk_khz,
>>  	signed int i;
>>
>>  	/* calculate the timeout range value */
>> -	i = log_2_n_round_up(timeout * clk_khz) - 16;
>> +	i = fls(timeout * clk_khz) - 16;
> 
> The two functions create different results:
> 
> generic_fls(15) = 4, log_2_n_round_up(15) = 4
> generic_fls(16) = 5, log_2_n_round_up(16) = 4
> generic_fls(17) = 5, log_2_n_round_up(17) = 5
> 
> Please, describe the effect of your change in the commit message.

Hm, then perhaps this should be

i = fls(timeout * clk_khz - 1) - 16;

--Sean