Date:   Fri, 26 Nov 2021 10:56:54 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Johan Hovold <johan@kernel.org>
Cc:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        Maarten Brock <m.brock@vanmierlo.com>, stable@vger.kernel.org,
        Karoly Pados <pados@pados.hu>
Subject: Re: [PATCH] USB: serial: cp210x: fix CP2105 GPIO registration
Message-ID: <YaCvZl2W4ZkrVPX+@kroah.com>
References: <20211126094348.31698-1-johan@kernel.org>
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On Fri, Nov 26, 2021 at 10:43:48AM +0100, Johan Hovold wrote:
> When generalising GPIO support and adding support for CP2102N, the GPIO
> registration for some CP2105 devices accidentally broke. Specifically,
> when all the pins of a port are in "modem" mode, and thus unavailable
> for GPIO use, the GPIO chip would now be registered without having
> initialised the number of GPIO lines. This would in turn be rejected by
> gpiolib and some errors messages would be printed (but importantly probe
> would still succeed).
> 
> Fix this by initialising the number of GPIO lines before registering the
> GPIO chip.
> 
> Note that as for the other device types, and as when all CP2105 pins are
> muxed for LED function, the GPIO chip is registered also when no pins
> are available for GPIO use.
> 
> Reported-by: Maarten Brock <m.brock@vanmierlo.com>
> Link: https://lore.kernel.org/r/5eb560c81d2ea1a2b4602a92d9f48a89@vanmierlo.com
> Fixes: c8acfe0aadbe ("USB: serial: cp210x: implement GPIO support for CP2102N")
> Cc: stable@vger.kernel.org      # 4.19
> Cc: Karoly Pados <pados@pados.hu>
> Signed-off-by: Johan Hovold <johan@kernel.org>


Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>