| Message ID | 4924f18fea9b028cab92ad4e79d957f5cb336b9c.1610976129.git.simon@simonsouth.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | pwm: rockchip: Eliminate potential race condition when probing | expand |
Hello Simon, On Tue, Jan 19, 2021 at 11:12:09AM -0500, Simon South wrote: > The documentation for clk_get_rate() in include/linux/clk.h states the > function's result is valid only for a clock source that has been > enabled. However, the Rockchip PWM driver uses this function in two places > to query the rate of a clock without first ensuring it is enabled. > > Fix this by modifying rockchip_pwm_get_state() and rockchip_pwm_apply() so > they enable a device's PWM clock before querying its rate (in the latter > case, the querying is actually done in rockchip_pwm_config()) and disable > the clock again before returning. > > Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > Signed-off-by: Simon South <simon@simonsouth.net> I already reviewed this patch in v3 and gave my Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> You make it a bit easier if you add the received tags for new iterations. Best regards Uwe
diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c index 228147e9bc6e..6ad7d0a50aed 100644 --- a/drivers/pwm/pwm-rockchip.c +++ b/drivers/pwm/pwm-rockchip.c @@ -72,6 +72,10 @@ static void rockchip_pwm_get_state(struct pwm_chip *chip, if (ret) return; + ret = clk_enable(pc->clk); + if (ret) + return; + clk_rate = clk_get_rate(pc->clk); tmp = readl_relaxed(pc->base + pc->data->regs.period); @@ -90,6 +94,7 @@ static void rockchip_pwm_get_state(struct pwm_chip *chip, else state->polarity = PWM_POLARITY_NORMAL; + clk_disable(pc->clk); clk_disable(pc->pclk); } @@ -189,6 +194,10 @@ static int rockchip_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, if (ret) return ret; + ret = clk_enable(pc->clk); + if (ret) + return ret; + pwm_get_state(pwm, &curstate); enabled = curstate.enabled; @@ -208,6 +217,7 @@ static int rockchip_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, } out: + clk_disable(pc->clk); clk_disable(pc->pclk); return ret;
The documentation for clk_get_rate() in include/linux/clk.h states the function's result is valid only for a clock source that has been enabled. However, the Rockchip PWM driver uses this function in two places to query the rate of a clock without first ensuring it is enabled. Fix this by modifying rockchip_pwm_get_state() and rockchip_pwm_apply() so they enable a device's PWM clock before querying its rate (in the latter case, the querying is actually done in rockchip_pwm_config()) and disable the clock again before returning. Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Simon South <simon@simonsouth.net> --- drivers/pwm/pwm-rockchip.c | 10 ++++++++++ 1 file changed, 10 insertions(+)