[BUG] mmc: core: adjust polling interval for CMD1

[H. Nikolaus Schaller]

Hi,
Jean Rene Dawin did report to me a problem on the Beagle Bone Black starting
with our disto kernel based on v5.17-rc1:

>> since kernel 5.17-rc1 I noticed slower emmc performance on Beaglebone
>> Black, but didn't check the logs.
>> When I tried to run 5.17.0-rc3-letux+ it booted fine, but during IO
>> traffic there were messages like
>> 
>> [  662.529584] mmc1: error -110 doing runtime resume
>> [  669.293590] mmc1: Card stuck being busy! __mmc_poll_for_busy
>> 
>> [  739.076072] mmc1: Timeout waiting for hardware interrupt.
>> [  739.145676] mmc1: sdhci: ============ SDHCI REGISTER DUMP ===========
>> [  739.231053] mmc1: sdhci: Sys addr:  0x00000000 | Version:  0x00003101
>> [  739.316472] mmc1: sdhci: Blk size:  0x00000200 | Blk cnt:  0x00000400
>> [  739.401937] mmc1: sdhci: Argument:  0x00342d30 | Trn mode: 0x00000023
>> [  739.487439] mmc1: sdhci: Present:   0x01f70000 | Host ctl: 0x00000000
>> [  739.573007] mmc1: sdhci: Power:     0x0000000f | Blk gap:  0x00000000
>> [  739.658609] mmc1: sdhci: Wake-up:   0x00000000 | Clock:    0x00003c07
>> [  739.744224] mmc1: sdhci: Timeout:   0x00000007 | Int stat: 0x00000002
>> [  739.829896] mmc1: sdhci: Int enab:  0x027f000b | Sig enab: 0x027f000b
>> [  739.915623] mmc1: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000001
>> [  740.001394] mmc1: sdhci: Caps:      0x07e10080 | Caps_1:   0x00000000
>> [  740.087208] mmc1: sdhci: Cmd:       0x0000193a | Max curr: 0x00000000
>> [  740.173051] mmc1: sdhci: Resp[0]:   0x00000900 | Resp[1]:  0x00000000
>> [  740.258928] mmc1: sdhci: Resp[2]:   0x00000000 | Resp[3]:  0x00000000
>> [  740.344854] mmc1: sdhci: Host ctl2: 0x00000000
>> [  740.402796] mmc1: sdhci: ============================================
>> 
>> and finally IO errors and a corrupted filesystem.
>> 
>> 5.17.0-rc4-letux+ shows the same behaviour.

I checked with my BeagleBoard Black (am3358) and can confirm this observation.
It happens only with the integrated eMMC but not with the µSD connected to
the other mmc interface.

A git bisect found:

76bfc7ccc2fa9d382576f6013b57a0ef93d5a722 is the first bad commit
commit 76bfc7ccc2fa9d382576f6013b57a0ef93d5a722
Author: Huijin Park <huijin.park@xxxxxxxxxxx>
Date:   Thu Nov 4 15:32:31 2021 +0900

  mmc: core: adjust polling interval for CMD1

  In mmc_send_op_cond(), loops are continuously performed at the same
  interval of 10 ms.  However the behaviour is not good for some eMMC
  which can be out from a busy state earlier than 10 ms if normal.

  Rather than fixing about the interval time in mmc_send_op_cond(),
  let's instead convert into using the common __mmc_poll_for_busy().

  The reason for adjusting the interval time is that it is important
  to reduce the eMMC initialization time, especially in devices that
  use eMMC as rootfs.

  Test log(eMMC:KLM8G1GETF-B041):

  before: 12 ms (0.311016 - 0.298729)
  [    0.295823] mmc0: starting CMD0 arg 00000000 flags 000000c0
  [    0.298729] mmc0: starting CMD1 arg 40000080 flags 000000e1<-start
  [    0.311016] mmc0: starting CMD1 arg 40000080 flags 000000e1<-finish
  [    0.311336] mmc0: starting CMD2 arg 00000000 flags 00000007

  after: 2 ms (0.301270 - 0.298762)
  [    0.295862] mmc0: starting CMD0 arg 00000000 flags 000000c0
  [    0.298762] mmc0: starting CMD1 arg 40000080 flags 000000e1<-start
  [    0.299067] mmc0: starting CMD1 arg 40000080 flags 000000e1
  [    0.299441] mmc0: starting CMD1 arg 40000080 flags 000000e1
  [    0.299879] mmc0: starting CMD1 arg 40000080 flags 000000e1
  [    0.300446] mmc0: starting CMD1 arg 40000080 flags 000000e1
  [    0.301270] mmc0: starting CMD1 arg 40000080 flags 000000e1<-finish
  [    0.301572] mmc0: starting CMD2 arg 00000000 flags 00000007

  Signed-off-by: Huijin Park <huijin.park@xxxxxxxxxxx>
  Link: https://lore.kernel.org/r/20211104063231.2115-3-huijin.park@xxxxxxxxxxx
  Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>

Reverting this makes v5.17-rc[1-4] work.

Any suggestions or fixes?

BR and thanks,
Nikolaus Schaller

Reported-by: jdawin@xxxxxxxxxxxxxxxxxxxxx