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For SD card reader devices that have the BLIST_IGN_MEDIA_CHANGE flag set, a MEDIUM MAY HAVE CHANGED unit attention is established after resuming from runtime suspend. Send a REQUEST SENSE to consume the UA. The "downside" is that for these devices we now rely on users to not change the medium (SD card) *during* a runtime suspend/resume cycle, i.e. when not unmounting. To enable runtime PM for an SD cardreader (device number 0:0:0:0), do: echo 0 > /sys/module/block/parameters/events_dfl_poll_msecs echo 1000 > /sys/bus/scsi/devices/0:0:0:0/power/autosuspend_delay_ms echo auto > /sys/bus/scsi/devices/0:0:0:0/power/control [mkp: use scsi_device flag instead of poking at BLIST] Link: https://lore.kernel.org/r/20210704075403.147114-3-martin.kepplinger@puri.sm Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.