* [PATCH] pwm: rcar: Use div64_ul instead of do_div
@ 2021-11-17 2:08 cgel.zte
2021-11-17 11:25 ` Uwe Kleine-König
0 siblings, 1 reply; 5+ messages in thread
From: cgel.zte @ 2021-11-17 2:08 UTC (permalink / raw)
To: thierry.reding
Cc: u.kleine-koenig, lee.jones, linux-pwm, linux-kernel,
Changcheng Deng, Zeal Robot
From: Changcheng Deng <deng.changcheng@zte.com.cn>
do_div() does a 64-by-32 division. If the divisor is unsigned long, using
div64_ul can avoid truncation to 32-bit.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
---
drivers/pwm/pwm-rcar.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c
index b437192380e2..fb475c188e1e 100644
--- a/drivers/pwm/pwm-rcar.c
+++ b/drivers/pwm/pwm-rcar.c
@@ -111,7 +111,7 @@ static int rcar_pwm_set_counter(struct rcar_pwm_chip *rp, int div, int duty_ns,
u32 cyc, ph;
one_cycle = (unsigned long long)NSEC_PER_SEC * 100ULL * (1 << div);
- do_div(one_cycle, clk_rate);
+ div64_ul(one_cycle, clk_rate);
tmp = period_ns * 100ULL;
do_div(tmp, one_cycle);
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] pwm: rcar: Use div64_ul instead of do_div
2021-11-17 2:08 [PATCH] pwm: rcar: Use div64_ul instead of do_div cgel.zte
@ 2021-11-17 11:25 ` Uwe Kleine-König
2021-11-17 13:01 ` [PATCH V2] " cgel.zte
0 siblings, 1 reply; 5+ messages in thread
From: Uwe Kleine-König @ 2021-11-17 11:25 UTC (permalink / raw)
To: cgel.zte
Cc: thierry.reding, lee.jones, linux-pwm, linux-kernel,
Changcheng Deng, Zeal Robot
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On Wed, Nov 17, 2021 at 02:08:54AM +0000, cgel.zte@gmail.com wrote:
> From: Changcheng Deng <deng.changcheng@zte.com.cn>
>
> do_div() does a 64-by-32 division. If the divisor is unsigned long, using
> div64_ul can avoid truncation to 32-bit.
>
> Reported-by: Zeal Robot <zealci@zte.com.cn>
> Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
> ---
> drivers/pwm/pwm-rcar.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c
> index b437192380e2..fb475c188e1e 100644
> --- a/drivers/pwm/pwm-rcar.c
> +++ b/drivers/pwm/pwm-rcar.c
> @@ -111,7 +111,7 @@ static int rcar_pwm_set_counter(struct rcar_pwm_chip *rp, int div, int duty_ns,
> u32 cyc, ph;
>
> one_cycle = (unsigned long long)NSEC_PER_SEC * 100ULL * (1 << div);
> - do_div(one_cycle, clk_rate);
> + div64_ul(one_cycle, clk_rate);
Same problem as with the atmel-hlcdc patch: The calling convention of
do_div and div64_ul are different and with the proposed patch the result
of the division is unused.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH V2] pwm: rcar: Use div64_ul instead of do_div
2021-11-17 11:25 ` Uwe Kleine-König
@ 2021-11-17 13:01 ` cgel.zte
2021-11-18 3:02 ` [PATCH V3] " cgel.zte
0 siblings, 1 reply; 5+ messages in thread
From: cgel.zte @ 2021-11-17 13:01 UTC (permalink / raw)
To: u.kleine-koenig
Cc: cgel.zte, deng.changcheng, lee.jones, linux-kernel, linux-pwm,
thierry.reding, zealci
From: Changcheng Deng <deng.changcheng@zte.com.cn>
do_div() does a 64-by-32 division. If the divisor is unsigned long, using
div64_ul can avoid truncation to 32-bit.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
---
drivers/pwm/pwm-rcar.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c
index b437192380e2..fb475c188e1e 100644
--- a/drivers/pwm/pwm-rcar.c
+++ b/drivers/pwm/pwm-rcar.c
@@ -111,7 +111,7 @@ static int rcar_pwm_set_counter(struct rcar_pwm_chip *rp, int div, int duty_ns,
u32 cyc, ph;
one_cycle = (unsigned long long)NSEC_PER_SEC * 100ULL * (1 << div);
- do_div(one_cycle, clk_rate);
+ one_cycle = div64_ul(one_cycle, clk_rate);
tmp = period_ns * 100ULL;
do_div(tmp, one_cycle);
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH V3] pwm: rcar: Use div64_ul instead of do_div
2021-11-17 13:01 ` [PATCH V2] " cgel.zte
@ 2021-11-18 3:02 ` cgel.zte
2021-11-18 8:41 ` Uwe Kleine-König
0 siblings, 1 reply; 5+ messages in thread
From: cgel.zte @ 2021-11-18 3:02 UTC (permalink / raw)
To: u.kleine-koenig
Cc: cgel.zte, deng.changcheng, lee.jones, linux-kernel, linux-pwm,
thierry.reding, zealci
From: Changcheng Deng <deng.changcheng@zte.com.cn>
do_div() does a 64-by-32 division. Here the divisor is an unsigned long
which on some platforms is 64 bit wide. So use div64_ul instead of do_div
to avoid a possible truncation.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
---
drivers/pwm/pwm-rcar.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c
index b437192380e2..fb475c188e1e 100644
--- a/drivers/pwm/pwm-rcar.c
+++ b/drivers/pwm/pwm-rcar.c
@@ -111,7 +111,7 @@ static int rcar_pwm_set_counter(struct rcar_pwm_chip *rp, int div, int duty_ns,
u32 cyc, ph;
one_cycle = (unsigned long long)NSEC_PER_SEC * 100ULL * (1 << div);
- do_div(one_cycle, clk_rate);
+ one_cycle = div64_ul(one_cycle, clk_rate);
tmp = period_ns * 100ULL;
do_div(tmp, one_cycle);
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH V3] pwm: rcar: Use div64_ul instead of do_div
2021-11-18 3:02 ` [PATCH V3] " cgel.zte
@ 2021-11-18 8:41 ` Uwe Kleine-König
0 siblings, 0 replies; 5+ messages in thread
From: Uwe Kleine-König @ 2021-11-18 8:41 UTC (permalink / raw)
To: cgel.zte
Cc: deng.changcheng, lee.jones, linux-kernel, linux-pwm,
thierry.reding, zealci
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On Thu, Nov 18, 2021 at 03:02:15AM +0000, cgel.zte@gmail.com wrote:
> From: Changcheng Deng <deng.changcheng@zte.com.cn>
>
> do_div() does a 64-by-32 division. Here the divisor is an unsigned long
> which on some platforms is 64 bit wide. So use div64_ul instead of do_div
> to avoid a possible truncation.
>
> Reported-by: Zeal Robot <zealci@zte.com.cn>
> Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
You're supposed to add a S-o-b line for yourself with a email address
that matches the sender of the patch.
Other than that the patch looks fine now.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-11-18 8:43 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2021-11-17 2:08 [PATCH] pwm: rcar: Use div64_ul instead of do_div cgel.zte
2021-11-17 11:25 ` Uwe Kleine-König
2021-11-17 13:01 ` [PATCH V2] " cgel.zte
2021-11-18 3:02 ` [PATCH V3] " cgel.zte
2021-11-18 8:41 ` Uwe Kleine-König
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