Andrew Halaney 408e28086f 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. 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>		2024-04-05 21:06:29 -04:00
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core	scsi: ufs: core: Perform read back after writing UTP_TASK_REQ_LIST_BASE_H	2024-04-05 21:06:29 -04:00
host	scsi: ufs: cdns-pltfrm: Perform read back after writing HCLKDIV	2024-04-05 21:06:29 -04:00
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