scsi: ufs: add quirk to disallow reset of interrupt aggregation

Some host controllers support interrupt aggregation but don't allow
resetting counter and timer in software.
Signed-off-by: Seungwon Jeon <essuuj@gmail.com>
Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufshcd.c

@@ -4659,7 +4659,8 @@ static void ufshcd_transfer_req_compl(struct ufs_hba *hba)
 	 * false interrupt if device completes another request after resetting
 	 * aggregation and before reading the DB.
 	 */
-	if (ufshcd_is_intr_aggr_allowed(hba))
+	if (ufshcd_is_intr_aggr_allowed(hba) &&
+	    !(hba->quirks & UFSHCI_QUIRK_SKIP_RESET_INTR_AGGR))
 		ufshcd_reset_intr_aggr(hba);
 
 	tr_doorbell = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);

drivers/scsi/ufs/ufshcd.h

@@ -600,6 +600,12 @@ struct ufs_hba {
 	 */
 	#define UFSHCI_QUIRK_BROKEN_REQ_LIST_CLR		0x100
 
+	/*
+	 * This quirk needs to be enabled if host controller doesn't allow
+	 * that the interrupt aggregation timer and counter are reset by s/w.
+	 */
+	#define UFSHCI_QUIRK_SKIP_RESET_INTR_AGGR		0x200
+
 	unsigned int quirks;	/* Deviations from standard UFSHCI spec. */
 
 	/* Device deviations from standard UFS device spec. */