target/linux/ath79/patches-6.6/100-reset-ath79-read-back-reset-register.patch

   1 From 661edfc3dab943a67c8821353b63cc23057f7ce9 Mon Sep 17 00:00:00 2001
   2 From: David Bauer <mail@david-bauer.net>
   3 Date: Tue, 9 Jan 2024 20:48:46 +0100
   4 Subject: [PATCH] reset: ath79: read back reset register
   5
   6 Read back the reset register in order to flush the cache. This fixes
   7 spurious reboot hangs on TP-Link TL-WDR3600 and TL-WDR4300 with Zentel
   8 DRAM chips.
   9
  10 This issue was fixed in the past, but switching to the reset-driver
  11 specific implementation removed the old fix.
  12
  13 Link: https://github.com/freifunk-gluon/gluon/issues/2904
  14 Link: https://github.com/openwrt/openwrt/issues/13043
  15 Link: https://dev.archive.openwrt.org/ticket/17839
  16 Link: f8a7bfe1cb2c ("MIPS: ath79: fix system restart")
  17
  18 Signed-off-by: David Bauer <mail@david-bauer.net>
  19 ---
  20  drivers/reset/reset-ath79.c | 2 ++
  21  1 file changed, 2 insertions(+)
  22
  23 --- a/drivers/reset/reset-ath79.c
  24 +++ b/drivers/reset/reset-ath79.c
  25 @@ -37,6 +37,8 @@ static int ath79_reset_update(struct res
  26         else
  27                 val &= ~BIT(id);
  28         writel(val, ath79_reset->base);
  29 +       /* Flush cache */
  30 +       readl(ath79_reset->base);
  31         spin_unlock_irqrestore(&ath79_reset->lock, flags);
  32
  33         return 0;