On Tue, May 30, 2017 at 02:42:13PM +0100, Alan Cox wrote: I sent a second patch recently:
https://patchwork.kernel.org/patch/9725625/ > > > Fixes: 18a4208826dd0a13eb06de724c86bba2c225f943 ("imx-serial: Reduce > > > RX DMA startup latency when opening for reading") > > > > > > Cc: cphe...@gmail.com > > > Cc: Peter Senna Tschudin <peter.se...@collabora.com> > > > Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> > > > Cc: Jiri Slaby <jsl...@suse.com> > > > Cc: linux-kernel@vger.kernel.org > > > Signed-off-by: Andrey Smirnov <andrew.smir...@gmail.com> > > > --- > > > > > > Not sure if this is the best way to solve the problem (hence the RFC > > > tag). If anyone has a better idea, or if there's a better fix for this > > > already, please let me know. > > > > IMO, the low level serial drivers shouldn't be accessing > > tty->tty_files in the first place. Is being opened for write-only that > > common and is skipping the DMA setup really necessary? > > Seconded - the Reduce RX DMA startup latency patch should just be > reverted (and shouldn't ever IMHO have gotten in). > > Not all readers and writers to a tty have a file handle any more anyway, > so it's not only icky and layer violating it's fundamentally broken > beyond the locking. > > Alan
