linux-kernel - [PATCH 2/3] ARM: at91: pm: fix MCKx restore routine

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Message-ID: <20250827145427.46819-3-nicolas.ferre@microchip.com>
Date: Wed, 27 Aug 2025 16:54:26 +0200
From: <nicolas.ferre@...rochip.com>
To: ARM Maintainers <arm@...nel.org>, Alexandre Belloni
	<alexandre.belloni@...tlin.com>, Ryan Wanner <ryan.wanner@...rochip.com>,
	Varshini Rajendran <varshini.rajendran@...rochip.com>, Claudiu Beznea
	<claudiu.beznea@...on.dev>
CC: <linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	Nicolas Ferre <nicolas.ferre@...rochip.com>
Subject: [PATCH 2/3] ARM: at91: pm: fix MCKx restore routine

From: Nicolas Ferre <nicolas.ferre@...rochip.com>

The at91_mckx_ps_restore() assembly function is responsible for setting
back MCKx system bus clocks after exiting low power modes.

Fix a typo and use tmp3 variable instead of tmp2 to correctly set MCKx
to previously saved sate.
Tmp2 was used without the needed changes in CSS and DIV. Moreover the
required bit 7, telling that MCR register's content is to be changed
(CMD/write), was not set.

Fix function comment to match tmp variables actually used.

Signed-off-by: Nicolas Ferre <nicolas.ferre@...rochip.com>
Fixes: 28eb1d40fe57 ("ARM: at91: pm: add support for MCK1..4 save/restore for ulp modes")
---
 arch/arm/mach-at91/pm_suspend.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-at91/pm_suspend.S b/arch/arm/mach-at91/pm_suspend.S
index e23b86834096..7e6c94f8edee 100644
--- a/arch/arm/mach-at91/pm_suspend.S
+++ b/arch/arm/mach-at91/pm_suspend.S
@@ -904,7 +904,7 @@ e_done:
 /**
  * at91_mckx_ps_restore: restore MCKx settings
  *
- * Side effects: overwrites tmp1, tmp2
+ * Side effects: overwrites tmp1, tmp2 and tmp3
  */
 .macro at91_mckx_ps_restore
 #ifdef CONFIG_SOC_SAMA7
@@ -980,7 +980,7 @@ r_ps:
 	bic	tmp3, tmp3, #AT91_PMC_MCR_V2_ID_MSK
 	orr	tmp3, tmp3, tmp1
 	orr	tmp3, tmp3, #AT91_PMC_MCR_V2_CMD
-	str	tmp2, [pmc, #AT91_PMC_MCR_V2]
+	str	tmp3, [pmc, #AT91_PMC_MCR_V2]
 
 	wait_mckrdy tmp1
 
-- 
2.43.0