Re: [PATCH v2] serial: 8250_dw: Prefer SRBR in bogus RX timeout workaround if available

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Mon, Sep 07, 2026 at 03:40:35PM +0800, Yicong Yang wrote:
> The DW uart could get into the cases where a bogus RX timeout
> interrupt is asserted but no available data. This could be
> workaround by doing a bogus read.
> 
> Currently the driver's using the standard RBR (receive buffer
> register) for this bogus read. However the reading of RBR
> in this case is allowed to raise a hardware error if vendor
> choose to implement in this way (our platform). It's also
> allowed to do the bogus read using SRBR (shadow RBR) for
> workaround which won't raise the hardware error. So change
> to use the SRBR to workaround the issue if it's available.

...

> struct dw8250_port_data {

>  
>  	/* RS485 variables */
>  	bool			hw_rs485_support;
>
> +	/* Shadow RBR offset, fallback to RBR if no shadow register support */

This comment is for "section", so split it to two

	/* Register offsets */
	/* Shadow RBR (if not defined RBR will be used) */

> +	unsigned int		srbr;

In APIs this defined as int, I would follow (however I agree that ideally in
all of them it should be unsigned).

	int		srbr;

>  };

-- 
With Best Regards,
Andy Shevchenko