Am Mittwoch, dem 06.10.2021 um 14:54 -0700 schrieb Bart Van Assche:
> The following query shows which drivers define callbacks that are
> called
> by the power management support code in the SCSI core (scsi_pm.c):
>
> $ git grep -nHEwA16 "$(echo $(git grep -h 'scsi_register_driver(&' |
> sed 's/.*&//;s/\..*//') | sed 's/ /|/g')" |
> grep '\.pm[[:blank:]]*=[[:blank:]]'
> drivers/scsi/sd.c-620- .pm = &sd_pm_ops,
> drivers/scsi/sr.c-100- .pm = &sr_pm_ops,
> drivers/scsi/ufs/ufshcd.c-9765- .pm = &ufshcd_wl_pm_ops,
>
> Since unconditionally runtime resuming a device during system resume
> is
> not necessary, remove that code. Modify the SCSI disk (sd) driver
> such
> that it follows the same approach as the UFS driver, namely to skip
> system suspend and resume for devices that are runtime suspended. The
> CD-ROM code does not need to be updated since its PM callbacks do not
> affect the device power state.
>
> This patch has been tested as follows:
>
> [ shell 1 ]
>
> cd /sys/kernel/debug/tracing
> grep -E
> 'blk_(pre|post)_runtime|runtime_(suspend|resume)|autosuspend_delay|pm
> _runtime_(get|put)' available_filter_functions |
> while read a b; do echo "$a"; done |
> grep -v __pm_runtime_resume >set_ftrace_filter
> echo function > current_tracer
> echo 1 > tracing_on
> cat trace_pipe
>
> [ shell 2 ]
>
> cd /sys/block/sr0
> # Increase the event poll interval to make it easier to derive from
> the
> # tracing output whether runtime power actions are the result of
> sg_inq.
> echo 30000 > events_poll_msecs
> cd device/power
> # Enable runtime power management.
> echo auto > control
> echo 1000 > autosuspend_delay_ms
> sleep 1
> # Verify in shell 1 that sr0 has been runtime suspended
> sg_inq /dev/sr0
> eject /dev/sr0
> sg_inq /dev/sr0
> # Disable runtime power management.
> echo on > control
>
> cd /sys/block/sda/device/power
> echo auto > control
> echo 1000 > autosuspend_delay_ms
> sleep 1
> # Verify in shell 1 that sr0 has been runtime suspended
> sg_inq /dev/sda
>
> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Hannes Reinecke <hare@xxxxxxxx>
> Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Cc: Martin Kepplinger <martin.kepplinger@xxxxxxx>
> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
> ---
> drivers/scsi/scsi_pm.c | 69 +++++++++-------------------------------
> --
> drivers/scsi/sd.c | 6 ++++
> 2 files changed, 20 insertions(+), 55 deletions(-)
>
Tested-by: Martin Kepplinger <martin.kepplinger@xxxxxxx>
on my system with a runtime-suspend enabled sd cardreader.
thanks,
martin
