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From aaaced6d2d6f796ed77e4725ed7ccbedb189c180 Mon Sep 17 00:00:00 2001
From: Romain Naour <romain.naour@gmail.com>
Date: Fri, 15 Jun 2018 17:43:38 +0200
Subject: [PATCH] Revert: serial: sh-sci: increase RX FIFO trigger defaults for
 (H)SCIF
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This reverts commit 18e8cf159177100e69d528293f8cf6875c0b1bca (kernel)

The last Qemu kernel update [1] introduced a regresion in sh4 SCIF
serial device. Some keyboard presses are very slow to be taken into
account, perhaps not even taken into account at all. This would
explain why our test infrastructure doesn’t manage to login as root
[2][3][4].

git bisect reported a kernel patch from 4.11, increasing RX FIFO
trigger defaults value for sh-sci (H)SCIF. The kernel patch itself
looks good but the Qemu emulation is not ready to handle this new
setting.

From Qemu (2.12.0): target/sh4/README.sh4
"Configuration of the second serial port (SCIF) is supported. FIFO
handling infrastructure has been started but is not completed yet."

In order to be able to test sh4 architecture with newer kernel,
revert to the old behaviour.

[1] https://git.buildroot.net/buildroot/commit/?id=03fb00f2175cdb4565e26fcb9b3da1c1059de1bd
[2] https://gitlab.com/free-electrons/toolchains-builder/-/jobs/72006425
[3] https://gitlab.com/free-electrons/toolchains-builder/-/jobs/72006427
[4] https://gitlab.com/free-electrons/toolchains-builder/-/jobs/72006426

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
---
 drivers/tty/serial/sh-sci.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index ab757546c6db..138e4dec44fb 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -2793,11 +2793,8 @@ static int sci_init_single(struct platform_device *dev,
 		sci_port->rx_trigger = 32;
 		break;
 	case PORT_SCIF:
-		if (p->regtype == SCIx_SH7705_SCIF_REGTYPE)
-			/* RX triggering not implemented for this IP */
-			sci_port->rx_trigger = 1;
-		else
-			sci_port->rx_trigger = 8;
+		/* RX triggering not implemented in Qemu emulation */
+		sci_port->rx_trigger = 1;
 		break;
 	default:
 		sci_port->rx_trigger = 1;
-- 
2.14.4