From 661edfc3dab943a67c8821353b63cc23057f7ce9 Mon Sep 17 00:00:00 2001
From: David Bauer <mail@david-bauer.net>
Date: Tue, 9 Jan 2024 20:48:46 +0100
Subject: [PATCH] reset: ath79: read back reset register

Read back the reset register in order to flush the cache. This fixes
spurious reboot hangs on TP-Link TL-WDR3600 and TL-WDR4300 with Zentel
DRAM chips.

This issue was fixed in the past, but switching to the reset-driver
specific implementation removed the old fix.

Link: https://github.com/freifunk-gluon/gluon/issues/2904
Link: https://github.com/openwrt/openwrt/issues/13043
Link: https://dev.archive.openwrt.org/ticket/17839
Link: f8a7bfe1cb2c ("MIPS: ath79: fix system restart")

Signed-off-by: David Bauer <mail@david-bauer.net>
---
 drivers/reset/reset-ath79.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/reset/reset-ath79.c
+++ b/drivers/reset/reset-ath79.c
@@ -37,6 +37,8 @@ static int ath79_reset_update(struct res
 	else
 		val &= ~BIT(id);
 	writel(val, ath79_reset->base);
+	/* Flush cache */
+	readl(ath79_reset->base);
 	spin_unlock_irqrestore(&ath79_reset->lock, flags);
 
 	return 0;
