On Tuesday 25 October 2022 12:18:56 Tim Harvey wrote:
On Tue, Sep 6, 2022 at 5:15 AM Johannes Schneider johannes.schneider@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.schneider@leica-geosystems.com Reviewed-by: Peng Fan peng.fan@nxp.com Reviewed-by: Fabio Estevam festevam@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);