Re: [PATCH v2] pwm: mtk_disp: Fix the disable flow of disp_pwm

On Mon, May 29, 2023 at 6:43 PM Matthias Brugger [off-list ref] wrote:

On 18/05/2023 13:52, Shuijing Li wrote:

quoted

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 <redacted>

We are missing a fixes tag here.
Fixes: 888a623db5d0 ("pwm: mtk-disp: Implement atomic API .apply()")


with that:
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>

Tested-by: Fei Shao <redacted>

quoted

---
Changes in v2:
Use
if (A && B) {
      something();
}
instead of
if (A) {
      if (B) {
              something();
      }
}
per suggestion from the previous thread:
https://lore.kernel.org/lkml/20230515140346.bxeu6xewi6a446nd@pengutronix.de/ (local)
---
  drivers/pwm/pwm-mtk-disp.c | 13 +++++--------
  1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/pwm/pwm-mtk-disp.c b/drivers/pwm/pwm-mtk-disp.c
index 79e321e96f56..2401b6733241 100644
--- a/drivers/pwm/pwm-mtk-disp.c
+++ b/drivers/pwm/pwm-mtk-disp.c

@@ -79,14 +79,11 @@ static int mtk_disp_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
      if (state->polarity != PWM_POLARITY_NORMAL)
              return -EINVAL;

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

              mdp->enabled = false;
              return 0;

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