2023-05-15 06:36:26

by Shuijing Li

[permalink] [raw]

Subject: [PATCH] pwm: mtk_disp: Fix the disable flow of disp_pwm

---

There is a flow error in the original mtk_disp_pwm_apply() function.
If this function is called when the clock is disabled, there will be a
chance to operate the disp_pwm register, resulting in disp_pwm exception.
Fix this accordingly.

Signed-off-by: Shuijing Li <[email protected]>
---
drivers/pwm/pwm-mtk-disp.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/pwm/pwm-mtk-disp.c b/drivers/pwm/pwm-mtk-disp.c
index 79e321e96f56..cb699fa9a5ae 100644
--- a/drivers/pwm/pwm-mtk-disp.c
+++ b/drivers/pwm/pwm-mtk-disp.c
@@ -80,10 +80,9 @@ static int mtk_disp_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
return -EINVAL;

if (!state->enabled) {
- mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN, mdp->data->enable_mask,
- 0x0);
-
if (mdp->enabled) {
+ mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN,
+ mdp->data->enable_mask, 0x0);
clk_disable_unprepare(mdp->clk_mm);
clk_disable_unprepare(mdp->clk_main);
}
--
2.40.1

2023-05-15 14:08:06

by Uwe Kleine-König

[permalink] [raw]

Subject: Re: [PATCH] pwm: mtk_disp: Fix the disable flow of disp_pwm

---

On Mon, May 15, 2023 at 02:18:45PM +0800, Shuijing Li wrote:
> There is a flow error in the original mtk_disp_pwm_apply() function.
> If this function is called when the clock is disabled, there will be a
> chance to operate the disp_pwm register, resulting in disp_pwm exception.
> Fix this accordingly.
>
> Signed-off-by: Shuijing Li <[email protected]>
> ---
> drivers/pwm/pwm-mtk-disp.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pwm/pwm-mtk-disp.c b/drivers/pwm/pwm-mtk-disp.c
> index 79e321e96f56..cb699fa9a5ae 100644
> --- a/drivers/pwm/pwm-mtk-disp.c
> +++ b/drivers/pwm/pwm-mtk-disp.c
> @@ -80,10 +80,9 @@ static int mtk_disp_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> return -EINVAL;
>
> if (!state->enabled) {
> - mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN, mdp->data->enable_mask,
> - 0x0);
> -
> if (mdp->enabled) {
> + mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN,
> + mdp->data->enable_mask, 0x0);
> clk_disable_unprepare(mdp->clk_mm);
> clk_disable_unprepare(mdp->clk_main);

Instead of

if (A) {
if (B) {
something();
}
}

you can make this

if (A && B) {
something();
}

Otherwise looks ok.

Best regards
Uwe

--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | https://www.pengutronix.de/ |

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