linux-kernel - Re: [PATCH v7 1/6] serial: 8250: make saved LSR larger

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Message-ID: <YqnmEGLLKrlR37HE@smile.fi.intel.com>
Date:   Wed, 15 Jun 2022 17:00:48 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc:     linux-serial@...r.kernel.org, Greg KH <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Paul Cercueil <paul@...pouillou.net>,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org,
        Lukas Wunner <lukas@...ner.de>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Lino Sanfilippo <LinoSanfilippo@....de>
Subject: Re: [PATCH v7 1/6] serial: 8250: make saved LSR larger

On Wed, Jun 15, 2022 at 03:48:24PM +0300, Ilpo Järvinen wrote:
> DW flags address received as BIT(8) in LSR. In order to not lose that
> on read, enlarge lsr_saved_flags to u16.
> 
> Adjust lsr/status variables and related call chains to use u16.
> Technically, some of these type conversion would not be needed but it
> doesn't hurt to be consistent.

...

>  static void exar_shutdown(struct uart_port *port)
>  {
> -	unsigned char lsr;
> +	u16 lsr;

I would take a chance and move it under the longer line(s), like after xmit
(taking into account given context).

>  	bool tx_complete = false;
>  	struct uart_8250_port *up = up_to_u8250p(port);
>  	struct circ_buf *xmit = &port->state->xmit;

...

>  int fsl8250_handle_irq(struct uart_port *port)
>  {
> -	unsigned char lsr, orig_lsr;
> +	u16 lsr, orig_lsr;

Ditto. And so on.

>  	unsigned long flags;
>  	unsigned int iir;
>  	struct uart_8250_port *up = up_to_u8250p(port);

-- 
With Best Regards,
Andy Shevchenko