[<prev] [next>] [day] [month] [year] [list]
Message-ID: <20240122-ufs-reset-ensure-effect-before-delay-v4-9-90a54c832508@redhat.com>
Date: Mon, 22 Jan 2024 11:24:05 -0600
From: Andrew Halaney <ahalaney@...hat.com>
To: Andy Gross <agross@...nel.org>,
Bjorn Andersson <andersson@...nel.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>,
Manivannan Sadhasivam <mani@...nel.org>,
"James E.J. Bottomley" <jejb@...ux.ibm.com>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
Hannes Reinecke <hare@...e.de>,
Janek Kotas <jank@...ence.com>,
Alim Akhtar <alim.akhtar@...sung.com>,
Avri Altman <avri.altman@....com>,
Bart Van Assche <bvanassche@....org>,
Can Guo <quic_cang@...cinc.com>
Cc: Andrew Halaney <ahalaney@...hat.com>,
Will Deacon <will@...nel.org>,
linux-arm-msm@...r.kernel.org,
linux-scsi@...r.kernel.org,
linux-kernel@...r.kernel.org,
Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH RFC v4 09/11] scsi: ufs: core: Perform read back after
disabling UIC_COMMAND_COMPL
Currently, the UIC_COMMAND_COMPL interrupt is disabled and a wmb() is
used to complete the register write before any following writes.
wmb() ensures the writes complete in that order, but completion doesn't
mean that it isn't stored in a buffer somewhere. The recommendation for
ensuring this bit has 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 bit hits the device. Because the wmb()'s
purpose wasn't to add extra ordering (on top of the ordering guaranteed
by writel()/readl()), it can safely be removed.
Fixes: d75f7fe495cf ("scsi: ufs: reduce the interrupts for power mode change requests")
Reviewed-by: Bart Van Assche <bvanassche@....org>
Reviewed-by: Can Guo <quic_cang@...cinc.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Signed-off-by: Andrew Halaney <ahalaney@...hat.com>
---
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 9b6355555897..9bf490bb8eed 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -4240,7 +4240,7 @@ static int ufshcd_uic_pwr_ctrl(struct ufs_hba *hba, struct uic_command *cmd)
* Make sure UIC command completion interrupt is disabled before
* issuing UIC command.
*/
- wmb();
+ ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
reenable_intr = true;
}
spin_unlock_irqrestore(hba->host->host_lock, flags);
--
2.43.0
Powered by blists - more mailing lists