From: Thierry Reding <thierry.reding@gmail.com>
To: Simon South <simon@simonsouth.net>
Cc: linux-pwm@vger.kernel.org, heiko@sntech.de,
linux-rockchip@lists.infradead.org,
u.kleine-koenig@pengutronix.de, lee.jones@linaro.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] pwm: rockchip: Keep enabled PWMs running while probing
Date: Wed, 23 Sep 2020 13:41:29 +0200 [thread overview]
Message-ID: <20200923114129.GB1846003@ulmo> (raw)
In-Reply-To: <20200919193306.1023-1-simon@simonsouth.net>
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On Sat, Sep 19, 2020 at 03:33:06PM -0400, Simon South wrote:
> 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>
> ---
> drivers/pwm/pwm-rockchip.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
Applied, thanks.
Thierry
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next prev parent reply other threads:[~2020-09-23 11:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-19 19:33 [PATCH v2] pwm: rockchip: Keep enabled PWMs running while probing Simon South
2020-09-21 8:01 ` Uwe Kleine-König
2020-09-23 10:49 ` Heiko Stübner
2020-09-23 11:41 ` Thierry Reding [this message]
2020-11-21 1:09 ` Trent Piepho
2020-11-30 0:36 ` Simon South
2020-11-30 0:44 ` [PATCH] pwm: rockchip: Eliminate potential race condition when probing Simon South
2020-12-10 17:48 ` Thierry Reding
2020-12-10 21:00 ` Trent Piepho
2020-12-11 10:44 ` Robin Murphy
2020-12-19 20:32 ` Simon South
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