Re: [PATCH v3] usbserial: cp210x - icount support for parity error checking

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Sun, Jun 21, 2020 at 10:21:11PM +0200, Jaromír Škorpil wrote:
> The current version of cp210x driver doesn't provide any way to detect
> a parity error in received data from userspace. Some serial protocols like
> STM32 bootloader protect data only by parity so application needs to
> know whether parity error happened to repeat peripheral data reading.
> 
> Added support for icount (ioctl TIOCGICOUNT) which sends GET_COMM_STATUS
> command to CP210X and according received flags increments fields for
> parity error, frame error, break and overrun. An application can detect
> an error condition after reading data from ttyUSB and reacts adequately.
> There is no impact for applications which don't call ioctl TIOCGICOUNT.
> 
> The flag "hardware overrun" is not examined because CP2102 sets this bit
> for the first received byte after openning of port which was previously
> closed with some unreaded data in buffer. This is confusing and checking
> "queue overrun" flag seems be enough.
> 
> Signed-off-by: Jaromír Škorpil <Jerry@jrr.cz>
> ---
> v2: Simplified counting - only queue overrun checked
> v3: Changed description + UTF-8 name  ;-)

Much nicer, thanks for the changes!

I'll let Johan comment on the actual patch itself, as he's the
maintainer of this driver/subsystems.

thanks,

greg k-h