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scsi: ufs: core: Perform read back after writing UTP_TASK_REQ_LIST_BASE_H
[ Upstream commit408e28086f
] 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:88441a8d35
("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-v5-7-181252004586@redhat.com Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -10353,7 +10353,7 @@ int ufshcd_system_restore(struct device *dev)
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* are updated with the latest queue addresses. Only after
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* updating these addresses, we can queue the new commands.
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*/
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mb();
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ufshcd_readl(hba, REG_UTP_TASK_REQ_LIST_BASE_H);
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/* Resuming from hibernate, assume that link was OFF */
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ufshcd_set_link_off(hba);
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