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

[Nicolas Frattaroli]

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 at collabora.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