[PATCH v2 0/3] scsi: add runtime PM workaround for SD cardreaders

[Martin Kepplinger]

revision history
----------------
v2:
 * move module parameter to sd
 * add Documentation

v1:
https://lore.kernel.org/linux-scsi/20210111152029.28426-1-martin.kepplinger@xxxxxxx/T/#t



hi,

In short: there are SD cardreaders that send MEDIA_CHANGED on
runtime resume. We cannot use runtime PM with these devices as
I/O basically always fails. I'd like to discuss a way to fix this
or at least allow users to work around this problem:

For the full background, the discussion started in June 2020 here:
https://lore.kernel.org/linux-scsi/20200623111018.31954-1-martin.kepplinger@xxxxxxx/

and I sent the first of these patches in August, as a reference:
https://lore.kernel.org/linux-scsi/20200824190400.12339-1-martin.kepplinger@xxxxxxx/
so this is where I'm following up on.

I'm not sure whether maintaining an in-kernel quirk for specific devices
makes sense so here I suggest adding a userspace knob. This way there's at
least a chance to use runtime PM for sd cardreaders that send MEDIA_CHANGED.

I'd appreciate any feedback.

Martin Kepplinger (3):
  scsi: add expecting_media_change flag to error path
  scsi: sd: add ignore_resume_medium_changed disk setting
  scsi: sd: Documentation: describe ignore_resume_medium_changed

 Documentation/scsi/sd-parameters.rst | 14 ++++++++
 drivers/scsi/scsi_error.c            | 36 +++++++++++++++++---
 drivers/scsi/sd.c                    | 50 +++++++++++++++++++++++++++-
 drivers/scsi/sd.h                    |  1 +
 include/scsi/scsi_device.h           |  1 +
 5 files changed, 96 insertions(+), 6 deletions(-)

-- 
2.20.1