Am Donnerstag, dem 07.10.2021 um 08:59 +0200 schrieb Martin Kepplinger:
> 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
>
Hi Bart,
I didn't get CC'd on the cover letter and just saw it. Code-wise I
think this makes sense, but what I tested was runtime-pm behaviour, not
(yet) together with system suspend. Just so you know.
thank you for improving this!
martin
