@@ -361,11 +361,16 @@ static int qcom_geni_serial_get_char(struct uart_port *uport)
return NO_POLL_CHAR;
if (word_cnt == 1 && (status & RX_LAST))
+ /*
+ * NOTE: If RX_LAST_BYTE_VALID is 0 it needs to be
+ * treated as if it was BYTES_PER_FIFO_WORD.
+ */
private_data->poll_cached_bytes_cnt =
(status & RX_LAST_BYTE_VALID_MSK) >>
RX_LAST_BYTE_VALID_SHFT;
- else
- private_data->poll_cached_bytes_cnt = 4;
+
+ if (private_data->poll_cached_bytes_cnt == 0)
+ private_data->poll_cached_bytes_cnt = BYTES_PER_FIFO_WORD;
private_data->poll_cached_bytes =
readl(uport->membase + SE_GENI_RX_FIFOn);
The commit e42d6c3ec0c7 ("serial: qcom_geni_serial: Make kgdb work even if UART isn't console") worked pretty well and I've been doing a lot of debugging with it. However, recently I typed "dmesg" in kdb and then held the space key down to scroll through the pagination. My device hung. This was repeatable and I found that it was introduced with the aforementioned commit. It turns out that there are some strange boundary cases in geni where in some weird situations it will signal RX_LAST but then will put 0 in RX_LAST_BYTE. This means that the entire last FIFO entry is valid. This weird corner case is handled in qcom_geni_serial_handle_rx() where you can see that we only honor RX_LAST_BYTE if RX_LAST is set _and_ RX_LAST_BYTE is non-zero. If either of these is not true we use BYTES_PER_FIFO_WORD (4) for the size of the last FIFO word. Let's fix kgdb. While at it, also use the proper #define for 4. Fixes: e42d6c3ec0c7 ("serial: qcom_geni_serial: Make kgdb work even if UART isn't console") Signed-off-by: Douglas Anderson <dianders@chromium.org> --- drivers/tty/serial/qcom_geni_serial.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)