scsi: ufs: core: Check LSDBS cap when !mcq

If the user sets use_mcq_mode to 0, the host will try to activate the LSDB
mode unconditionally even when the LSDBS of device HCI cap is 1. This makes
commands time out and causes device probing to fail.

To prevent that problem, check the LSDBS cap when MCQ is not supported.

Signed-off-by: Kyoungrul Kim <k831.kim@samsung.com>
Link: https://lore.kernel.org/r/20240709232520epcms2p8ebdb5c4fccc30a6221390566589bf122@epcms2p8
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/ufs/core/ufshcd.c

@@ -2416,7 +2416,17 @@ static inline int ufshcd_hba_capabilities(struct ufs_hba *hba)
 		return err;
 	}
 
+	/*
+	 * The UFSHCI 3.0 specification does not define MCQ_SUPPORT and
+	 * LSDB_SUPPORT, but [31:29] as reserved bits with reset value 0s, which
+	 * means we can simply read values regardless of version.
+	 */
 	hba->mcq_sup = FIELD_GET(MASK_MCQ_SUPPORT, hba->capabilities);
+	/*
+	 * 0h: legacy single doorbell support is available
+	 * 1h: indicate that legacy single doorbell support has been removed
+	 */
+	hba->lsdb_sup = !FIELD_GET(MASK_LSDB_SUPPORT, hba->capabilities);
 	if (!hba->mcq_sup)
 		return 0;
 
@@ -10494,6 +10504,12 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 	}
 
 	if (!is_mcq_supported(hba)) {
+		if (!hba->lsdb_sup) {
+			dev_err(hba->dev, "%s: failed to initialize (legacy doorbell mode not supported)\n",
+				__func__);
+			err = -EINVAL;
+			goto out_disable;
+		}
 		err = scsi_add_host(host, hba->dev);
 		if (err) {
 			dev_err(hba->dev, "scsi_add_host failed\n");

include/ufs/ufshcd.h

@@ -1109,6 +1109,7 @@ struct ufs_hba {
 	bool ext_iid_sup;
 	bool scsi_host_added;
 	bool mcq_sup;
+	bool lsdb_sup;
 	bool mcq_enabled;
 	struct ufshcd_res_info res[RES_MAX];
 	void __iomem *mcq_base;

include/ufs/ufshci.h

@@ -77,6 +77,7 @@ enum {
 	MASK_OUT_OF_ORDER_DATA_DELIVERY_SUPPORT	= 0x02000000,
 	MASK_UIC_DME_TEST_MODE_SUPPORT		= 0x04000000,
 	MASK_CRYPTO_SUPPORT			= 0x10000000,
+	MASK_LSDB_SUPPORT			= 0x20000000,
 	MASK_MCQ_SUPPORT			= 0x40000000,
 };