patch "serial: 8250_mtk: Make sure to select the right FEATURE_SEL" added to tty-linus

patch "serial: 8250_mtk: Make sure to select the right FEATURE_SEL" added to tty-linus

[gregkh]

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 my tty git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


From 6f81fdded0d024c7d4084d434764f30bca1cd6b1 Mon Sep 17 00:00:00 2001
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Date: Wed, 27 Apr 2022 15:23:27 +0200
Subject: serial: 8250_mtk: Make sure to select the right FEATURE_SEL

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@collabora.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220427132328.228297-3-angelogioacchino.delregno@collabora.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/8250/8250_mtk.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index cd62a5f34014..28e36459642c 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -54,6 +54,9 @@
 #define MTK_UART_TX_TRIGGER	1
 #define MTK_UART_RX_TRIGGER	MTK_UART_RX_SIZE
 
+#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,
@@ -569,6 +572,10 @@ 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));
-- 
2.36.0