Commit 11be938a authored Jan 19, 2021 by Simon South Committed by Thierry Reding Jan 20, 2021

pwm: rockchip: Enable clock before calling clk_get_rate()

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>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

parent d21ba5d6

drivers/pwm/pwm-rockchip.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -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;