From d6a513a78492b09fbe41a9922948a7371c821c5b Mon Sep 17 00:00:00 2001 From: Andrew Halaney Date: Fri, 29 Mar 2024 15:46:49 -0500 Subject: [PATCH] UPSTREAM: scsi: ufs: core: Perform read back after writing UTP_TASK_REQ_LIST_BASE_H Currently, the UTP_TASK_REQ_LIST_BASE_L/UTP_TASK_REQ_LIST_BASE_H regs are written to and then completed with an mb(). mb() ensures that the write completes, but completion doesn't mean that it isn't stored in a buffer somewhere. The recommendation for ensuring these bits have taken effect on the device is to perform a read back to force it to make it all the way to the device. This is documented in device-io.rst and a talk by Will Deacon on this can be seen over here: https://youtu.be/i6DayghhA8Q?si=MiyxB5cKJXSaoc01&t=1678 Let's do that to ensure the bits hit the device. Because the mb()'s purpose wasn't to add extra ordering (on top of the ordering guaranteed by writel()/readl()), it can safely be removed. Bug: 254441685 Fixes: 88441a8d355d ("scsi: ufs: core: Add hibernation callbacks") Reviewed-by: Manivannan Sadhasivam Reviewed-by: Bart Van Assche Reviewed-by: Can Guo Signed-off-by: Andrew Halaney Link: https://lore.kernel.org/r/20240329-ufs-reset-ensure-effect-before-delay-v5-7-181252004586@redhat.com Signed-off-by: Martin K. Petersen (cherry picked from commit 408e28086f1c7a6423efc79926a43d7001902fae) Signed-off-by: Lee Jones Change-Id: Iadf1f45aebea54393365a5387d35440aa5df3e00 --- drivers/ufs/core/ufshcd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c index bd8cbd64758d..2779cded8141 100644 --- a/drivers/ufs/core/ufshcd.c +++ b/drivers/ufs/core/ufshcd.c @@ -10257,7 +10257,7 @@ int ufshcd_system_restore(struct device *dev) * are updated with the latest queue addresses. Only after * updating these addresses, we can queue the new commands. */ - mb(); + ufshcd_readl(hba, REG_UTP_TASK_REQ_LIST_BASE_H); /* Resuming from hibernate, assume that link was OFF */ ufshcd_set_link_off(hba);