Hi George,
On Thu, May 9, 2019 at 4:44 PM George G. Davis <[email protected]> wrote:
> As noted in commit 84b40e3b57ee ("serial: 8250: omap: Disable DMA for
> console UART"), UART console lines use low-level PIO only access functions
> which will conflict with use of the line when DMA is enabled, e.g. when
> the console line is also used for systemd messages. So disable DMA
> support for UART console lines.
>
> Fixes: https://patchwork.kernel.org/patch/10929511/
> Reported-by: Michael Rodin <[email protected]>
> Cc: Eugeniu Rosca <[email protected]>
> Signed-off-by: George G. Davis <[email protected]>
I think this makes sense. In addition to OMAP 8250, the same approach
is used in the Mediatek 8250 and iMX serial drivers.
Regardless, this is definitely better than removing the "dmas" properties
from DT, as DT describes hardware, not usage policies.
Anyone else with a comment?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
On Mon, May 13, 2019 at 01:13:16PM +0200, Geert Uytterhoeven wrote:
> Hi George,
>
> On Thu, May 9, 2019 at 4:44 PM George G. Davis <[email protected]> wrote:
> > As noted in commit 84b40e3b57ee ("serial: 8250: omap: Disable DMA for
> > console UART"), UART console lines use low-level PIO only access functions
> > which will conflict with use of the line when DMA is enabled, e.g. when
> > the console line is also used for systemd messages. So disable DMA
> > support for UART console lines.
> >
> > Fixes: https://patchwork.kernel.org/patch/10929511/
> > Reported-by: Michael Rodin <[email protected]>
> > Cc: Eugeniu Rosca <[email protected]>
> > Signed-off-by: George G. Davis <[email protected]>
>
> I think this makes sense. In addition to OMAP 8250, the same approach
> is used in the Mediatek 8250 and iMX serial drivers.
>
> Regardless, this is definitely better than removing the "dmas" properties
> from DT, as DT describes hardware, not usage policies.
+1
> Anyone else with a comment?
Reviewed-by: Simon Horman <[email protected]>