linux-kernel - Re: [PATCH 06/36] usb: serial: ti_usb_3410_5052: Do not use _

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Date:	Fri, 15 Jul 2016 13:03:17 +0200
From:	Johan Hovold <johan@...nel.org>
To:	Mathieu OTHACEHE <m.othacehe@...il.com>
Cc:	johan@...nel.org, gregkh@...uxfoundation.org,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 06/36] usb: serial: ti_usb_3410_5052: Do not use __uX
 types

On Thu, May 12, 2016 at 10:48:38AM +0200, Mathieu OTHACEHE wrote:
> __uX types should only be used for user-space interactions.
> 
> Signed-off-by: Mathieu OTHACEHE <m.othacehe@...il.com>
> ---
>  drivers/usb/serial/ti_usb_3410_5052.c | 66 ++++++++++++++++++-----------------
>  1 file changed, 34 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/usb/serial/ti_usb_3410_5052.c b/drivers/usb/serial/ti_usb_3410_5052.c
> index af4e145..164e07b 100644
> --- a/drivers/usb/serial/ti_usb_3410_5052.c
> +++ b/drivers/usb/serial/ti_usb_3410_5052.c
> @@ -179,23 +179,23 @@
>  
>  /* Config struct */
>  struct ti_uart_config {
> -	__u16	wBaudRate;
> -	__u16	wFlags;
> -	__u8	bDataBits;
> -	__u8	bParity;
> -	__u8	bStopBits;
> +	__be16	wBaudRate;
> +	__be16	wFlags;

While I have nothing against replacing the __u<width>, this makes me
worried. How, if at all, is the endianess of these fields handled in the
code?

Ok, I see now it's using cpu_to_be16s after writing host-endian data
into it. Could you clean that to use cpu_to_be16 instead (you may need
to update an error message too)?

Note that the wBaudRate assignment was still using __u16 after this
patch.

> +	u8	bDataBits;
> +	u8	bParity;
> +	u8	bStopBits;
>  	char	cXon;
>  	char	cXoff;
> -	__u8	bUartMode;
> +	u8	bUartMode;
>  } __packed;
 
>  static int ti_write_byte(struct usb_serial_port *port,
> -			struct ti_device *tdev, unsigned long addr,
> -			__u8 mask, __u8 byte)
> +			 struct ti_device *tdev, unsigned long addr,
> +			 u8 mask, u8 byte)
>  {
>  	int status;
>  	unsigned int size;
> @@ -1659,10 +1661,10 @@ static int ti_do_download(struct usb_device *dev, int pipe,
>  	int len;
>  
>  	for (pos = sizeof(struct ti_firmware_header); pos < size; pos++)
> -		cs = (__u8)(cs + buffer[pos]);
> +		cs = (u8)(cs + buffer[pos]);
>  
>  	header = (struct ti_firmware_header *)buffer;
> -	header->wLength = cpu_to_le16((__u16)(size
> +	header->wLength = cpu_to_le16((u16)(size
>  					- sizeof(struct ti_firmware_header)));

Cast not needed.

Thanks,
Johan