[PATCH] scsi: ufs: core: Skip link param validation when lanes_per_direction is unset

[Daejun Park]

ufshcd_validate_link_params(), added by commit e72323f3b09f ("scsi: ufs:
core: Configure only active lanes during link"), is called
unconditionally from ufshcd_link_startup() and fails link startup with
-ENOLINK when the connected lane count read from the device differs from
hba->lanes_per_direction.

lanes_per_direction is only set by ufshcd-pltfrm (default 2, or the
"lanes-per-direction" devicetree property); ufshcd-pci controllers
(e.g. Intel) leave it 0. As the device always reports >= 1 connected
lanes, the check can never match and link startup always fails.
Reproduced with QEMU's UFS device.

Skip the check when lanes_per_direction is unset: with no expected value
to validate against, restore the behaviour from before that commit.

Fixes: e72323f3b09f ("scsi: ufs: core: Configure only active lanes during link")
Signed-off-by: Daejun Park <daejun7.park@xxxxxxxxxxx>
---
 drivers/ufs/core/ufshcd.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 1aad1c03c3fc..0a510f43ce76 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -5222,6 +5222,16 @@ static int ufshcd_validate_link_params(struct ufs_hba *hba)
 {
 	int ret, val;
 
+	/*
+	 * lanes_per_direction is only populated by the platform glue (it
+	 * defaults to 2 or is read from the "lanes-per-direction" devicetree
+	 * property). Controllers probed via ufshcd-pci leave it unset (0), in
+	 * which case there is no expected lane count to validate the connected
+	 * lanes against. Skip the check instead of failing link startup.
+	 */
+	if (!hba->lanes_per_direction)
+		return 0;
+
 	ret = ufshcd_dme_get(hba, UIC_ARG_MIB(PA_CONNECTEDTXDATALANES),
 			     &val);
 	if (ret)

base-commit: 016d484531e3169cd7bcb26e0ac2c5523080809f
-- 
2.43.0