v2 -> v3: add fixes
v1 -> v2: does skipping only for zero offset

These are ROC type things that means their values
are cleared when the SFRs are read.
They are usually read in ISR when an UIC error occur.
Thus, their values would be zero at many cases. And
there might be a little bit risky when they are read to
be cleared before the ISR reads them, e.g. the case that
a command is timed-out, ufshcd_dump_regs is called in
ufshcd_abort and an UIC error occurs at the nearly
same time. In this case, ISR will be called but UFS error handler
will not be scheduled.
This patch is to make UFS driver not read those SFRs in the
dump function, i.e. ufshcd_dump_regs.

Fixes: d67247566450 ("scsi: ufs: Use explicit access size in ufshcd_dump_regs")
Signed-off-by: Kiwoong Kim <kwmad.kim@samsung.com>
---
 drivers/scsi/ufs/ufshcd.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 460d2b4..7f2a1ed 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -115,8 +115,13 @@ int ufshcd_dump_regs(struct ufs_hba *hba, size_t offset, size_t len,
 	if (!regs)
 		return -ENOMEM;
 
-	for (pos = 0; pos < len; pos += 4)
+	for (pos = 0; pos < len; pos += 4) {
+		if (offset == 0 &&
+		    pos >= REG_UIC_ERROR_CODE_PHY_ADAPTER_LAYER &&
+		    pos <= REG_UIC_ERROR_CODE_DME)
+			continue;
 		regs[pos / 4] = ufshcd_readl(hba, offset + pos);
+	}
 
 	ufshcd_hex_dump(prefix, regs, len);
 	kfree(regs);
-- 
2.7.4

On Thu, 31 Mar 2022 10:24:05 +0900, Kiwoong Kim wrote:

> v2 -> v3: add fixes
> v1 -> v2: does skipping only for zero offset
> 
> These are ROC type things that means their values
> are cleared when the SFRs are read.
> They are usually read in ISR when an UIC error occur.
> Thus, their values would be zero at many cases. And
> there might be a little bit risky when they are read to
> be cleared before the ISR reads them, e.g. the case that
> a command is timed-out, ufshcd_dump_regs is called in
> ufshcd_abort and an UIC error occurs at the nearly
> same time. In this case, ISR will be called but UFS error handler
> will not be scheduled.
> This patch is to make UFS driver not read those SFRs in the
> dump function, i.e. ufshcd_dump_regs.
> 
> [...]

Applied to 5.19/scsi-queue, thanks!

[1/1] scsi: ufs: exclude UECxx from SFR dump list
      https://git.kernel.org/mkp/scsi/c/ef60031022eb

-- 
Martin K. Petersen	Oracle Linux Engineering

Kiwoong,

> This patch is to make UFS driver not read those SFRs in the dump
> function, i.e. ufshcd_dump_regs.

Applied to 5.19/scsi-staging, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering