6.6-stable review patch. If anyone has any objections, please let me know.
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From: Andrew Halaney ahalaney@redhat.com
[ Upstream commit 408e28086f1c7a6423efc79926a43d7001902fae ]
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.
Fixes: 88441a8d355d ("scsi: ufs: core: Add hibernation callbacks") Reviewed-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org Reviewed-by: Bart Van Assche bvanassche@acm.org Reviewed-by: Can Guo quic_cang@quicinc.com Signed-off-by: Andrew Halaney ahalaney@redhat.com Link: https://lore.kernel.org/r/20240329-ufs-reset-ensure-effect-before-delay-v5-7... Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 344806330be16..cd1b9db8543dc 100644 --- a/drivers/ufs/core/ufshcd.c +++ b/drivers/ufs/core/ufshcd.c @@ -10152,7 +10152,7 @@ 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);