linux-kernel - [PATCH v3 21/24] scsi: ufs: mediatek: Back up idle timer in per-instance struct

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Message-Id: <20251023-mt8196-ufs-v3-21-0f04b4a795ff@collabora.com>
Date: Thu, 23 Oct 2025 21:49:39 +0200
From: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
To: Alim Akhtar <alim.akhtar@...sung.com>, 
 Avri Altman <avri.altman@....com>, Bart Van Assche <bvanassche@....org>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Chunfeng Yun <chunfeng.yun@...iatek.com>, Vinod Koul <vkoul@...nel.org>, 
 Kishon Vijay Abraham I <kishon@...nel.org>, 
 Peter Wang <peter.wang@...iatek.com>, Stanley Jhu <chu.stanley@...il.com>, 
 "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>, 
 "Martin K. Petersen" <martin.petersen@...cle.com>, 
 Philipp Zabel <p.zabel@...gutronix.de>, Liam Girdwood <lgirdwood@...il.com>, 
 Mark Brown <broonie@...nel.org>
Cc: Louis-Alexis Eyraud <louisalexis.eyraud@...labora.com>, 
 kernel@...labora.com, linux-scsi@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org, 
 linux-phy@...ts.infradead.org, 
 Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
Subject: [PATCH v3 21/24] scsi: ufs: mediatek: Back up idle timer in
 per-instance struct

The MediaTek UFS driver uses a function-scope static variable to back up
a hardware register across a power change in the
ufs_mtk_pwr_change_notify function. This is dangerous, as it's only
correct if only ever one instance of the driver is loaded, which isn't
true if there's more than one device on a SoC that needs it, or it
otherwise gets loaded a second time.

Back it up into a member of the host struct instead, as this struct is
per-instance. Rework the function to not use a pointless "ret" local as
well.

Fixes: f5ca8d0c7a63 ("scsi: ufs: host: mediatek: Disable auto-hibern8 during power mode changes")
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
---
 drivers/ufs/host/ufs-mediatek.c | 20 ++++++++------------
 drivers/ufs/host/ufs-mediatek.h |  1 +
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/drivers/ufs/host/ufs-mediatek.c b/drivers/ufs/host/ufs-mediatek.c
index 6f54c5a35dc4..38698fbbd228 100644
--- a/drivers/ufs/host/ufs-mediatek.c
+++ b/drivers/ufs/host/ufs-mediatek.c
@@ -1385,28 +1385,24 @@ static int ufs_mtk_pwr_change_notify(struct ufs_hba *hba,
 				const struct ufs_pa_layer_attr *dev_max_params,
 				struct ufs_pa_layer_attr *dev_req_params)
 {
-	int ret = 0;
-	static u32 reg;
+	struct ufs_mtk_host *host = ufshcd_get_variant(hba);

 	switch (stage) {
 	case PRE_CHANGE:
 		if (ufshcd_is_auto_hibern8_supported(hba)) {
-			reg = ufshcd_readl(hba, REG_AUTO_HIBERNATE_IDLE_TIMER);
+			host->hibernate_idle_timer = ufshcd_readl(
+				hba, REG_AUTO_HIBERNATE_IDLE_TIMER);
 			ufs_mtk_auto_hibern8_disable(hba);
 		}
-		ret = ufs_mtk_pre_pwr_change(hba, dev_max_params,
-					     dev_req_params);
-		break;
+		return ufs_mtk_pre_pwr_change(hba, dev_max_params, dev_req_params);
 	case POST_CHANGE:
 		if (ufshcd_is_auto_hibern8_supported(hba))
-			ufshcd_writel(hba, reg, REG_AUTO_HIBERNATE_IDLE_TIMER);
-		break;
-	default:
-		ret = -EINVAL;
-		break;
+			ufshcd_writel(hba, host->hibernate_idle_timer,
+				      REG_AUTO_HIBERNATE_IDLE_TIMER);
+		return 0;
 	}

-	return ret;
+	return -EINVAL;
 }

 static int ufs_mtk_unipro_set_lpm(struct ufs_hba *hba, bool lpm)
diff --git a/drivers/ufs/host/ufs-mediatek.h b/drivers/ufs/host/ufs-mediatek.h
index fa27ab4d6d6c..e5a3f70e7024 100644
--- a/drivers/ufs/host/ufs-mediatek.h
+++ b/drivers/ufs/host/ufs-mediatek.h
@@ -187,6 +187,7 @@ struct ufs_mtk_host {
 	u16 ref_clk_gating_wait_us;
 	u32 ip_ver;
 	bool legacy_ip_ver;
+	u32 hibernate_idle_timer;

 	bool mcq_set_intr;
 	bool is_mcq_intr_enabled;

-- 
2.51.1.dirty