Re: [PATCH] serial: Do not treat the IIR register as a bitfield

[Andy Shevchenko]

On Wed, 2017-03-29 at 20:44 +0200, Olliver Schinagl wrote:
> It seems that at some point, someone made the assumption that the UART
> Interrupt ID Register was a bitfield and started to check if certain
> bits where set.
> 
> Actually however the register contains interrupt ID's where only the
> MSB
> seems to be used singular and the rest share at least one bit. Thus
> doing bitfield operations is wrong.
> 
> This patch cleans up the serial_reg include file by ordering it and
> replacing the UART_IIR_ID 'mask' with a proper mask for the register.
> The OMAP uart appears to have used the two commonly 'reserved' bits 4
> and 5 and thus get an UART_IIR_EXT_MASK for these two bits.
> 
> This patch then goes over all UART_IIR_* users and changes the code
> from
> bitfield checking, to ID checking instead.


Looking to implementation I would rather go with some helper like

int serial_in_IIR(port, [additional mask])
{
 return port->serial_in(port, UART_IIR) & (_IIR_MASK [| additional
mask]);
}

-- 
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy