scsi: ufs: skip devoting device ref_clk during clock gating

Voting/devoting device ref_clk source could be time consuming hence add
support to allow ufs variant to decide if it wants to control ref_clk
during aggressive clock gating or not. This clock should still be gated
off during runtime/system suspend.

Change-Id: Ibec8cc8b3689ff4e2418039e74dbf311e589157e
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>

drivers/scsi/ufs/ufs-qcom.c

@@ -1720,6 +1720,13 @@ static int ufs_qcom_init(struct ufs_hba *hba)
 	host->hba = hba;
 	ufshcd_set_variant(hba, host);
 
+	/*
+	 * voting/devoting device ref_clk source is time consuming hence
+	 * skip devoting it during aggressive clock gating. This clock
+	 * will still be gated off during runtime suspend.
+	 */
+	hba->no_ref_clk_gating = true;
+
 	err = ufs_qcom_ice_get_dev(host);
 	if (err == -EPROBE_DEFER) {
 		/*

drivers/scsi/ufs/ufshcd.c

@@ -1270,7 +1270,7 @@ static void ufshcd_gate_work(struct work_struct *work)
 
 	ufshcd_suspend_clkscaling(hba);
 
-	if (!ufshcd_is_link_active(hba))
+	if (!ufshcd_is_link_active(hba) && !hba->no_ref_clk_gating)
 		ufshcd_setup_clocks(hba, false);
 	else
 		/* If link is active, device ref_clk can't be switched off */

drivers/scsi/ufs/ufshcd.h

@@ -841,6 +841,9 @@ struct ufs_hba {
 	bool is_urgent_bkops_lvl_checked;
 
 	struct rw_semaphore clk_scaling_lock;
+
+	/* If set, don't gate device ref_clk during clock gating */
+	bool no_ref_clk_gating;
 };
 
 /* Returns true if clocks can be gated. Otherwise false */