[PATCH 5.15 220/230] Revert "serial: 8250_mtk: Make sure to select the right FEATURE_SEL"

Greg Kroah-Hartman
2022-07-11T10:05:21Z

From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

commit f0136f65285bcfb7e8f90d1013723076a35acd51 upstream.

It was found that some MediaTek SoCs are incompatible with this
change. Also, this register was mistakenly understood as it was
related to the 16550A register layout selection but, at least
on some IPs, if not all, it's related to something else unknown.

This reverts commit 6f81fdded0d024c7d4084d434764f30bca1cd6b1.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Fixes: 6f81fdded0d0 ("serial: 8250_mtk: Make sure to select the right FEATURE_SEL")
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Link: https://lore.kernel.org/r/20220510122620.150342-1-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 deletions(-)

--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -57,9 +57,6 @@
#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,
@@ -575,10 +572,6 @@ static int mtk8250_probe(struct platform
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));