* [PATCH] serial: zynq: Use DIV_ROUND_CLOSEST() to calcurate divider value
@ 2022-07-13 1:38 Kunihiko Hayashi
2022-07-15 10:48 ` Michal Simek
0 siblings, 1 reply; 3+ messages in thread
From: Kunihiko Hayashi @ 2022-07-13 1:38 UTC (permalink / raw)
To: Michal Simek; +Cc: u-boot, Kunihiko Hayashi
Since the calulation of "bgen" is rounded down, using a higher
baudrate will result in a larger difference from the actual
baudrate. Should use DIV_ROUND_CLOSEST() like the Linux driver.
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
---
drivers/serial/serial_zynq.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/serial/serial_zynq.c b/drivers/serial/serial_zynq.c
index 83adfb5fb98a..857c570c5836 100644
--- a/drivers/serial/serial_zynq.c
+++ b/drivers/serial/serial_zynq.c
@@ -75,7 +75,7 @@ static void _uart_zynq_serial_setbrg(struct uart_zynq *regs,
* Find acceptable values for baud generation.
*/
for (bdiv = 4; bdiv < 255; bdiv++) {
- bgen = clock / (baud * (bdiv + 1));
+ bgen = DIV_ROUND_CLOSEST(clock, (baud * (bdiv + 1)));
if (bgen < 2 || bgen > 65535)
continue;
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] serial: zynq: Use DIV_ROUND_CLOSEST() to calcurate divider value
2022-07-13 1:38 [PATCH] serial: zynq: Use DIV_ROUND_CLOSEST() to calcurate divider value Kunihiko Hayashi
@ 2022-07-15 10:48 ` Michal Simek
2022-07-16 16:34 ` Kunihiko Hayashi
0 siblings, 1 reply; 3+ messages in thread
From: Michal Simek @ 2022-07-15 10:48 UTC (permalink / raw)
To: Kunihiko Hayashi; +Cc: u-boot
On 7/13/22 03:38, Kunihiko Hayashi wrote:
> Since the calulation of "bgen" is rounded down, using a higher
> baudrate will result in a larger difference from the actual
> baudrate. Should use DIV_ROUND_CLOSEST() like the Linux driver.
>
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
> ---
> drivers/serial/serial_zynq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/serial/serial_zynq.c b/drivers/serial/serial_zynq.c
> index 83adfb5fb98a..857c570c5836 100644
> --- a/drivers/serial/serial_zynq.c
> +++ b/drivers/serial/serial_zynq.c
> @@ -75,7 +75,7 @@ static void _uart_zynq_serial_setbrg(struct uart_zynq *regs,
> * Find acceptable values for baud generation.
> */
> for (bdiv = 4; bdiv < 255; bdiv++) {
> - bgen = clock / (baud * (bdiv + 1));
> + bgen = DIV_ROUND_CLOSEST(clock, (baud * (bdiv + 1)));
Applied but I have removed one level of () in second parameter which is not needed.
Thanks,
Michal
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] serial: zynq: Use DIV_ROUND_CLOSEST() to calcurate divider value
2022-07-15 10:48 ` Michal Simek
@ 2022-07-16 16:34 ` Kunihiko Hayashi
0 siblings, 0 replies; 3+ messages in thread
From: Kunihiko Hayashi @ 2022-07-16 16:34 UTC (permalink / raw)
To: Michal Simek; +Cc: u-boot
Hi Michal,
On 2022/07/15 19:48, Michal Simek wrote:
>
>
> On 7/13/22 03:38, Kunihiko Hayashi wrote:
>> Since the calulation of "bgen" is rounded down, using a higher
>> baudrate will result in a larger difference from the actual
>> baudrate. Should use DIV_ROUND_CLOSEST() like the Linux driver.
>>
>> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
>> ---
>> drivers/serial/serial_zynq.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/serial/serial_zynq.c b/drivers/serial/serial_zynq.c
>> index 83adfb5fb98a..857c570c5836 100644
>> --- a/drivers/serial/serial_zynq.c
>> +++ b/drivers/serial/serial_zynq.c
>> @@ -75,7 +75,7 @@ static void _uart_zynq_serial_setbrg(struct uart_zynq
>> *regs,
>> * Find acceptable values for baud generation.
>> */
>> for (bdiv = 4; bdiv < 255; bdiv++) {
>> - bgen = clock / (baud * (bdiv + 1));
>> + bgen = DIV_ROUND_CLOSEST(clock, (baud * (bdiv + 1)));
>
> Applied but I have removed one level of () in second parameter which is not
> needed.
Sorry I forgot to remove it.
Thanks for pointing out.
---
Best Regards
Kunihiko Hayashi
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-07-13 1:38 [PATCH] serial: zynq: Use DIV_ROUND_CLOSEST() to calcurate divider value Kunihiko Hayashi
2022-07-15 10:48 ` Michal Simek
2022-07-16 16:34 ` Kunihiko Hayashi
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