On Tuesday 25 October 2022 12:18:56 Tim Harvey wrote:
> On Tue, Sep 6, 2022 at 5:15 AM Johannes Schneider
> <johannes.schnei...@leica-geosystems.com> wrote:
> >
> > only waiting for TXEMPTY leads to corrupted messages going over the
> > wire - which is fixed by making use of the FIFO
> >
> > this change is following the linux kernel uart driver
> > (drivers/tty/serial/imx.c), which also checks UTS_TXFULL
> > instead of UTS_TXEMPTY
> >
> > Signed-off-by: Johannes Schneider <johannes.schnei...@leica-geosystems.com>
> > Reviewed-by: Peng Fan <peng....@nxp.com>
> > Reviewed-by: Fabio Estevam <feste...@denx.de>
> > ---
> >
> > (no changes since v1)
> >
> > drivers/serial/serial_mxc.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/serial/serial_mxc.c b/drivers/serial/serial_mxc.c
> > index ee17a960d4..af1fd1ea9b 100644
> > --- a/drivers/serial/serial_mxc.c
> > +++ b/drivers/serial/serial_mxc.c
> > @@ -311,7 +311,7 @@ static int mxc_serial_putc(struct udevice *dev, const
> > char ch)
> > struct mxc_serial_plat *plat = dev_get_plat(dev);
> > struct mxc_uart *const uart = plat->reg;
> >
> > - if (!(readl(&uart->ts) & UTS_TXEMPTY))
> > + if (readl(&uart->ts) & UTS_TXFULL)
> > return -EAGAIN;
> >
> > writel(ch, &uart->txd);
> > --
> > 2.25.1
> >
>
> Johannes,
>
> Since this patch I find an issue with an IMX6 board of mine gwventana:
>
> Prior to this patch the board boots with:
> DRAM: 1 GiB
> GSCv2 : v52 0x9981 RST:VIN WDT:disabled board_temp:43C
> RTC : 1970-01-01 0:56:15 UTC
> Core: 67 devices, 22 uclasses, devicetree: separate
> WDT: Started watchdog@20bc000 with servicing every 1000ms (60s timeout)
> NAND: 2048 MiB
> ...
>
> and following this patch I get:
> ...
> DRAM: 1 GiB
> GSCv2 : v52 0x9981 RST:VIN WDT:disabled board_temp:29C
> RTC : 1970-01-01 ~�KW�'$H�$V�W��Y.KH�� uclasses, devicetree: separate
> WDT: Started watchdog@20bc000 with servicing every 1000ms (60s timeout)
> NAND: 2048 MiB
> ...
>
> The RTC line is displayed from drivers/misc/gsc.c and the Core: comes
> from dm_announce. Somehow in between the FIFO does not get drained
> before dm_announce gets called.
>
> Adding a delay after the RTC print or reverting this patch.
>
> Any ideas?
>
> Best Regards,
>
> Tim
Hello! I do not have any MXC hardware but I see there one issue.
mxc_serial_putc() function probably should not return -EAGAIN when
device is busy. But instead it should wait until it is ready.
Could you try to change code to following?
while (readl(&uart->ts) & UTS_TXFULL)
;
writel(ch, &uart->txd);
