linux-kernel - [PATCH 5.18 064/339] Revert "serial: 8250_mtk: Make sure to select the right FEATURE

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Message-Id: <20220613094928.464950203@linuxfoundation.org>
Date:   Mon, 13 Jun 2022 12:08:09 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        "kernelci.org bot" <bot@...nelci.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.18 064/339] Revert "serial: 8250_mtk: Make sure to select the right FEATURE_SEL"

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

[ Upstream commit f0136f65285bcfb7e8f90d1013723076a35acd51 ]

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@...labora.com>
Fixes: 6f81fdded0d0 ("serial: 8250_mtk: Make sure to select the right FEATURE_SEL")
Reported-by: "kernelci.org bot" <bot@...nelci.org>
Link: https://lore.kernel.org/r/20220510122620.150342-1-angelogioacchino.delregno@collabora.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/tty/serial/8250/8250_mtk.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index 21053db93ff1..54051ec7b499 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -54,9 +54,6 @@
 #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 */
-
 #define MTK_UART_XON1		40	/* I/O: Xon character 1 */
 #define MTK_UART_XOFF1		42	/* I/O: Xoff character 1 */
 
@@ -575,10 +572,6 @@ 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));
-- 
2.35.1