@@ -171,8 +171,7 @@ static void pwm_imx27_get_state(struct pwm_chip *chip,
tmp = NSEC_PER_SEC * (u64)(val);
state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, pwm_clk);
- if (!state->enabled)
- pwm_imx27_clk_disable_unprepare(imx);
+ pwm_imx27_clk_disable_unprepare(imx);
}
static void pwm_imx27_sw_reset(struct pwm_chip *chip)
@@ -307,6 +306,8 @@ MODULE_DEVICE_TABLE(of, pwm_imx27_dt_ids);
static int pwm_imx27_probe(struct platform_device *pdev)
{
struct pwm_imx27_chip *imx;
+ int ret;
+ u32 pwmcr;
imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
if (imx == NULL)
@@ -349,6 +350,15 @@ static int pwm_imx27_probe(struct platform_device *pdev)
if (IS_ERR(imx->mmio_base))
return PTR_ERR(imx->mmio_base);
+ ret = pwm_imx27_clk_prepare_enable(imx);
+ if (ret)
+ return ret;
+
+ /* keep clks on if pwm is running */
+ pwmcr = readl(imx->mmio_base + MX3_PWMCR);
+ if (!(pwmcr & MX3_PWMCR_EN))
+ pwm_imx27_clk_disable_unprepare(imx);
+
return pwmchip_add(&imx->chip);
}
Up to now the .probe function didn't enable clks and relied on the core to call the .get_state() callback to have the clk running. The latter enabled the needed clocks and kept them running if the PWM is enabled. This only works correctly if the .get_state() callback is called exactly once and this single call happens before unused clocks are disabled by the clk core. The former wasn't true for a short period while commit 01ccf903edd6 ("pwm: Let pwm_get_state() return the last implemented state") applied and not not reverted yet and might become wrong in the future. The latter isn't true any more since commit cfc4c189bc70 ("pwm: Read initial hardware state at request time") which results in a running PWM being stopped at boot time if for example the consumer lives in a kernel module that is only loaded after the clk core disabled unused clocks. So ensure .probe() is left with the clocks on if the PWM is running and .get_state() disables everything it enabled. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- drivers/pwm/pwm-imx27.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)