This is a note to let you know that I've just added the patch titled
serial: 8250_mtk: Make sure to select the right FEATURE_SEL
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-8250_mtk-make-sure-to-select-the-right-featur.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e542f7f58f6a46e18587ecd4bfe0488c19596b25
Author: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Date: Wed Apr 27 15:23:27 2022 +0200
serial: 8250_mtk: Make sure to select the right FEATURE_SEL
[ Upstream commit 6f81fdded0d024c7d4084d434764f30bca1cd6b1 ]
Set the FEATURE_SEL at probe time to make sure that BIT(0) is enabled:
this guarantees that when the port is configured as AP UART, the
right register layout is interpreted by the UART IP.
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220427132328.228297-3-angelogioacchino.delregno@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index de48a58460f4..de57f47635cd 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -57,6 +57,9 @@
#define MTK_UART_XON1 40 /* I/O: Xon character 1 */
#define MTK_UART_XOFF1 42 /* I/O: Xoff character 1 */
+#define MTK_UART_FEATURE_SEL 39 /* Feature Selection register */
+#define MTK_UART_FEAT_NEWRMAP BIT(0) /* Use new register map */
+
#ifdef CONFIG_SERIAL_8250_DMA
enum dma_rx_status {
DMA_RX_START = 0,
@@ -572,6 +575,10 @@ static int mtk8250_probe(struct platform_device *pdev)
uart.dma = data->dma;
#endif
+ /* Set AP UART new register map */
+ writel(MTK_UART_FEAT_NEWRMAP, uart.port.membase +
+ (MTK_UART_FEATURE_SEL << uart.port.regshift));
+
/* Disable Rate Fix function */
writel(0x0, uart.port.membase +
(MTK_UART_RATE_FIX << uart.port.regshift));
