scsi: ufs: host: mediatek: Fine-tune clock scaling

Disable clock scaling for UFS versions below 4.0. Clock scaling is
unnecessary for these versions, and this change ensures that the feature
is only enabled for compatible UFS versions.

Signed-off-by: Peter Wang <peter.wang@mediatek.com>
Link: https://lore.kernel.org/r/20250811131423.3444014-5-peter.wang@mediatek.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: ptr324

drivers/ufs/host/ufs-mediatek.c

@@ -29,6 +29,7 @@
 #include "ufs-mediatek-sip.h"
 
 static int  ufs_mtk_config_mcq(struct ufs_hba *hba, bool irq);
+static void _ufs_mtk_clk_scale(struct ufs_hba *hba, bool scale_up);
 
 #define CREATE_TRACE_POINTS
 #include "ufs-mediatek-trace.h"
@@ -1144,6 +1145,17 @@ static void ufs_mtk_fix_ahit(struct ufs_hba *hba)
 	ufs_mtk_setup_clk_gating(hba);
 }
 
+static void ufs_mtk_fix_clock_scaling(struct ufs_hba *hba)
+{
+	/* UFS version is below 4.0, clock scaling is not necessary */
+	if ((hba->dev_info.wspecversion < 0x0400)  &&
+		ufs_mtk_is_clk_scale_ready(hba)) {
+		hba->caps &= ~UFSHCD_CAP_CLK_SCALING;
+
+		_ufs_mtk_clk_scale(hba, false);
+	}
+}
+
 static void ufs_mtk_init_mcq_irq(struct ufs_hba *hba)
 {
 	struct ufs_mtk_host *host = ufshcd_get_variant(hba);
@@ -1774,6 +1786,7 @@ static void ufs_mtk_fixup_dev_quirks(struct ufs_hba *hba)
 	ufs_mtk_vreg_fix_vcc(hba);
 	ufs_mtk_vreg_fix_vccqx(hba);
 	ufs_mtk_fix_ahit(hba);
+	ufs_mtk_fix_clock_scaling(hba);
 }
 
 static void ufs_mtk_event_notify(struct ufs_hba *hba,