linux-kernel - [PATCH] soc: ti: pm33xx: fix resume from non-rtc suspend modes

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Message-Id: <20230831151232.4169624-1-arsalan.awan@siemens.com>
Date:   Thu, 31 Aug 2023 20:12:32 +0500
From:   "Arsalan H. Awan" <arsalanhassanawan@...il.com>
To:     ssantosh@...nel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     "Arsalan H. Awan" <arsalan.awan@...mens.com>
Subject: [PATCH] soc: ti: pm33xx: fix resume from non-rtc suspend modes

The am33xx_pm_rtc_setup() checks if the rtc device is available or not.
It configures the rtc if device is available, otherwise keeps the rtc
mode suspend functionality disabled.

In case a platform does not use the internal rtc and it is needed to
disable the rtc-only suspend mode, the resume from deepsleep or standby
modes fails right now becasue the am33xx_pm_end() tries to access the
rtc device and that results in a NULL pointer dereference.

This patch moves the rtc-only code within the correct bounds.
Otherwise, we get a kernel OOPS with a NULL pointer dereference on
resume when we try to access omap_rtc_scratch0.

Signed-off-by: Arsalan H. Awan <arsalan.awan@...mens.com>
---
 drivers/soc/ti/pm33xx.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/soc/ti/pm33xx.c b/drivers/soc/ti/pm33xx.c
index f04c21157904..e3ccb0bb198a 100644
--- a/drivers/soc/ti/pm33xx.c
+++ b/drivers/soc/ti/pm33xx.c
@@ -305,10 +305,6 @@ static void am33xx_pm_end(void)
 	u32 val = 0;
 	struct nvmem_device *nvmem;

-	nvmem = devm_nvmem_device_get(&omap_rtc->dev, "omap_rtc_scratch0");
-	if (IS_ERR(nvmem))
-		return;
-
 	m3_ipc->ops->finish_low_power(m3_ipc);
 	if (rtc_only_idle) {
 		if (retrigger_irq) {
@@ -324,6 +320,10 @@ static void am33xx_pm_end(void)
 				       + retrigger_irq / 32 * 4);
 		}

+		nvmem = devm_nvmem_device_get(&omap_rtc->dev, "omap_rtc_scratch0");
+		if (IS_ERR(nvmem))
+			return;
+
 		nvmem_device_write(nvmem, RTC_SCRATCH_MAGIC_REG * 4, 4,
 				   (void *)&val);
 	}
-- 
2.25.1