Patch "scsi: ufs: core: Check LSDBS cap when !mcq" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     scsi-ufs-core-check-lsdbs-cap-when-mcq.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 432fb759066d16caef22de7fcbfa1403c0ab7c8b
Author: Kyoungrul Kim <k831.kim@xxxxxxxxxxx>
Date:   Wed Jul 10 08:25:20 2024 +0900

    scsi: ufs: core: Check LSDBS cap when !mcq
    
    [ Upstream commit 0c60eb0cc320fffbb8b10329d276af14f6f5e6bf ]
    
    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@xxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240709232520epcms2p8ebdb5c4fccc30a6221390566589bf122@epcms2p8
    Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
    Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 94edac17b95f8..bfa9f457f24ea 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -2281,7 +2281,17 @@ 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;
 
@@ -10386,6 +10396,12 @@ 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");
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index e4da397360682..2a7d6f269d9e3 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -1064,6 +1064,7 @@ 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;
diff --git a/include/ufs/ufshci.h b/include/ufs/ufshci.h
index d5accacae6bca..ae93b30d25893 100644
--- a/include/ufs/ufshci.h
+++ b/include/ufs/ufshci.h
@@ -75,6 +75,7 @@ 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,
 };