From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Simon South <simon@simonsouth.net>
Cc: tpiepho@gmail.com, thierry.reding@gmail.com,
lee.jones@linaro.org, heiko@sntech.de, bbrezillon@kernel.org,
linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-rockchip@lists.infradead.org
Subject: Re: [PATCH v2 1/3] pwm: rockchip: Enable APB clock during register access while probing
Date: Mon, 21 Dec 2020 09:22:09 +0100 [thread overview]
Message-ID: <20201221082209.z4hkrcym4o7xhmmb@pengutronix.de> (raw)
In-Reply-To: <49ceda3def13f6186073745e99d7315c974bfa81.1608407584.git.simon@simonsouth.net>
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Hello,
On Sat, Dec 19, 2020 at 03:44:08PM -0500, Simon South wrote:
> Commit 457f74abbed0 ("pwm: rockchip: Keep enabled PWMs running while
> probing") modified rockchip_pwm_probe() to access a PWM device's registers
> directly to check whether or not the device is running, but did not also
> change the function to first enable the device's APB clock to be certain
> the device can respond. This risks hanging the kernel on systems with PWM
> devices that use more than a single clock.
>
> Avoid this by enabling the device's APB clock before accessing its
> registers (and disabling the clock when register access is complete).
>
> Fixes: 457f74abbed0 ("pwm: rockchip: Keep enabled PWMs running while probing")
> Reported-by: Thierry Reding <thierry.reding@gmail.com>
> Suggested-by: Trent Piepho <tpiepho@gmail.com>
> Signed-off-by: Simon South <simon@simonsouth.net>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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next prev parent reply other threads:[~2020-12-21 8:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-19 20:44 [PATCH v2 0/3] pwm: rockchip: Eliminate potential race condition when probing Simon South
2020-12-19 20:44 ` [PATCH v2 1/3] pwm: rockchip: Enable APB clock during register access while probing Simon South
2020-12-21 8:22 ` Uwe Kleine-König [this message]
2020-12-19 20:44 ` [PATCH v2 2/3] pwm: rockchip: Eliminate potential race condition when probing Simon South
2020-12-21 8:50 ` Uwe Kleine-König
2020-12-22 16:26 ` Simon South
2020-12-19 20:44 ` [PATCH v2 3/3] pwm: rockchip: Do not start PWMs not already running Simon South
2020-12-21 9:05 ` Uwe Kleine-König
2020-12-22 16:32 ` Simon South
2020-12-22 17:23 ` Robin Murphy
2020-12-22 17:43 ` Simon South
2020-12-21 9:16 ` [PATCH v2 0/3] pwm: rockchip: Eliminate potential race condition when probing Uwe Kleine-König
2020-12-22 16:34 ` Simon South
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