Date:   Mon, 1 Nov 2021 08:59:02 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Zijun Hu <zijuhu@codeaurora.org>
Cc:     robh@kernel.org, jirislaby@kernel.org,
        linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-bluetooth@vger.kernel.org, Zijun Hu <quic_zijuhu@quicinc.com>
Subject: Re: [PATCH v1] serdev: Add interface serdev_device_ioctl
Message-ID: <YX+eRgCrUs2Y5iaX@kroah.com>
References: <1635753048-5289-1-git-send-email-zijuhu@codeaurora.org>
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On Mon, Nov 01, 2021 at 03:50:48PM +0800, Zijun Hu wrote:
> From: Zijun Hu <quic_zijuhu@quicinc.com>
> 
> For serdev_device which is mounted at virtual tty port, tty ioctl()
> maybe be used to make serdev_device ready to talk with tty port, so
> add interface serdev_device_ioctl().
> 
> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
> ---
>  drivers/tty/serdev/core.c           | 11 +++++++++++
>  drivers/tty/serdev/serdev-ttyport.c | 12 ++++++++++++
>  include/linux/serdev.h              |  9 +++++++++
>  3 files changed, 32 insertions(+)
> 
> diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
> index f1324fe99378..c0f6cd64716b 100644
> --- a/drivers/tty/serdev/core.c
> +++ b/drivers/tty/serdev/core.c
> @@ -405,6 +405,17 @@ int serdev_device_set_tiocm(struct serdev_device *serdev, int set, int clear)
>  }
>  EXPORT_SYMBOL_GPL(serdev_device_set_tiocm);
>  
> +int serdev_device_ioctl(struct serdev_device *serdev, unsigned int cmd, unsigned long arg)
> +{
> +	struct serdev_controller *ctrl = serdev->ctrl;
> +
> +	if (!ctrl || !ctrl->ops->ioctl)
> +		return -EOPNOTSUPP;

Wrong error for returning that an ioctl is not handled :(

Anyway, what in-tree driver needs this functionality?  Why does serdev
need any ioctl commands?

thanks,

greg k-h