linux-kernel - Re: [PATCH v2] can: tcan4x5x: fix reset gpio usage during probe

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Message-ID: <20250715-eccentric-mussel-of-glee-bcdb1c-mkl@pengutronix.de>
Date: Tue, 15 Jul 2025 12:02:04 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Brett Werling <brett.werling@...min.com>
Cc: linux-can@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Vincent Mailhol <mailhol.vincent@...adoo.fr>, bwerl.dev@...il.com
Subject: Re: [PATCH v2] can: tcan4x5x: fix reset gpio usage during probe

On 11.07.2025 09:17:28, Brett Werling wrote:
> Fixes reset GPIO usage during probe by ensuring we retrieve the GPIO and
> take the device out of reset (if it defaults to being in reset) before
> we attempt to communicate with the device. This is achieved by moving
> the call to tcan4x5x_get_gpios() before tcan4x5x_find_version() and
> avoiding any device communication while getting the GPIOs. Once we
> determine the version, we can then take the knowledge of which GPIOs we
> obtained and use it to decide whether we need to disable the wake or
> state pin functions within the device.
> 
> This change is necessary in a situation where the reset GPIO is pulled
> high externally before the CPU takes control of it, meaning we need to
> explicitly bring the device out of reset before we can start
> communicating with it at all.
> 
> This also has the effect of fixing an issue where a reset of the device
> would occur after having called tcan4x5x_disable_wake(), making the
> original behavior not actually disable the wake. This patch should now
> disable wake or state pin functions well after the reset occurs.
> 
> Signed-off-by: Brett Werling <brett.werling@...min.com>

Thanks for the patch, applied to linux-can, added stable on Cc.

regards,
Marc

PS: start a new thread for a new version of a patch, don't reply to the
old version.

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
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