diff options
author | Mattijs Korpershoek | 2023-06-06 18:07:48 +0200 |
---|---|---|
committer | Neil Armstrong | 2023-06-07 10:09:20 +0200 |
commit | afa85a2247297d660a63295bfbdd6e24e8e56902 (patch) | |
tree | 6aed0e68852c6effb842841d90d68754ac08cf99 | |
parent | fadf83c86d7252df2b50ba526ffeea95658cb5b5 (diff) |
serial: meson: fix meson_serial_pending() tx logic
According to the dm_serial_ops documentation, pending() should:
> @return number of waiting characters, 0 for none, -ve on error
And:
> It is acceptable to return 1 if an indeterminant number
> of characters is waiting.
With the current implementation, we have:
* FIFO is full -> pending() returns 0
* FIFO is partially used -> pending() returns 1
* FIFO is empty -> pending() returns 1
This is not the same as what the documentation requires.
Moreover, since [1], arm reset now flushes all console devices
(including serial) before the cpu gets reset.
Because of the flawed logic:
=> reset # user calls reset
flush() is called
_serial_flush() is called
ops->pending(dev, false) # never returns false
# board hangs indefinitely without resetting.
Fix it by using AML_UART_TX_EMPTY instead of AML_UART_TX_FULL.
[1] commit c5f4cdb8eb60 ("console: Use flush() before panic and reset"),
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20230606-fix-meson-serial-pending-v1-1-6a54d4a01f76@baylibre.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
-rw-r--r-- | drivers/serial/serial_meson.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/serial/serial_meson.c b/drivers/serial/serial_meson.c index d026f5a7a8e..934de2ab235 100644 --- a/drivers/serial/serial_meson.c +++ b/drivers/serial/serial_meson.c @@ -201,7 +201,10 @@ static int meson_serial_pending(struct udevice *dev, bool input) return true; } else { - return !(status & AML_UART_TX_FULL); + if (status & AML_UART_TX_EMPTY) + return false; + + return true; } } |