From: Simon South simon@simonsouth.net
[ Upstream commit 457f74abbed060a0395f75ab5297f2d76cada516 ]
Following commit cfc4c189bc70 ("pwm: Read initial hardware state at request time") the Rockchip PWM driver can no longer assume a device's pwm_state structure has been populated after a call to pwmchip_add(). Consequently, the test in rockchip_pwm_probe() intended to prevent the driver from stopping PWM devices already enabled by the bootloader no longer functions reliably and this can lead to the kernel hanging during startup, particularly on devices like the Pinebook Pro that use a PWM-controlled backlight for their display.
Avoid this by querying the device directly at probe time to determine whether or not it is enabled.
Fixes: cfc4c189bc70 ("pwm: Read initial hardware state at request time") Signed-off-by: Simon South simon@simonsouth.net Reviewed-by: Uwe Kleine-König u.kleine-koenig@pengutronix.de Reviewed-by: Heiko Stuebner heiko@sntech.de Signed-off-by: Thierry Reding thierry.reding@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pwm/pwm-rockchip.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c index eb8c9cb645a6c..098e94335cb5b 100644 --- a/drivers/pwm/pwm-rockchip.c +++ b/drivers/pwm/pwm-rockchip.c @@ -288,6 +288,7 @@ static int rockchip_pwm_probe(struct platform_device *pdev) const struct of_device_id *id; struct rockchip_pwm_chip *pc; struct resource *r; + u32 enable_conf, ctrl; int ret, count;
id = of_match_device(rockchip_pwm_dt_ids, &pdev->dev); @@ -362,7 +363,9 @@ static int rockchip_pwm_probe(struct platform_device *pdev) }
/* Keep the PWM clk enabled if the PWM appears to be up and running. */ - if (!pwm_is_enabled(pc->chip.pwms)) + enable_conf = pc->data->enable_conf; + ctrl = readl_relaxed(pc->base + pc->data->regs.ctrl); + if ((ctrl & enable_conf) != enable_conf) clk_disable(pc->clk);
return 0;