| Message ID | 20210628133412.1172068-1-martin.kepplinger@puri.sm |
|---|---|
| Headers | show |
| Series | fix runtime PM for SD card readers | expand |
On 6/28/21 6:34 AM, Martin Kepplinger wrote: > +static int sd_resume_runtime(struct device *dev) > +{ > + struct scsi_disk *sdkp = dev_get_drvdata(dev); > + struct scsi_device *sdp; > + int timeout, retries, res; > + struct scsi_sense_hdr my_sshdr; Since the sense data is ignored, consider removing the "my_sshdr" declaration and passing NULL as sense pointer to scsi_execute(). > + if (!sdkp) /* E.g.: runtime resume at the start of sd_probe() */ > + return 0; Are you sure that this code is necessary? There is an scsi_autopm_get_device(sdp) call at the start of sd_probe() and scsi_autopm_put_device(sdp) call at the end of sd_probe(). In other words, no runtime suspend will happen between the device_initialize(&sdkp->dev) call in sd_probe() and the dev_set_drvdata(dev, sdkp) call in the same function. > + if (sdp->sdev_bflags & BLIST_MEDIA_CHANGE) { > + for (retries = 3; retries > 0; --retries) { > + unsigned char cmd[10] = { 0 }; > + > + cmd[0] = REQUEST_SENSE; Please define the CDB as follows: static const u8 cmd[10] = { REQUEST_SENSE }; > + /* > + * Leave the rest of the command zero to indicate > + * flush everything. > + */ Shouldn't this comment appear above the CDB definition? Also, what does "flush everything" mean? According to SPC sense data is discarded from the device while processing REQUEST SENSE, no matter what the value of the ALLOCATION LENGTH parameter in that command is. From SPC-6: "the REQUEST SENSE command with any allocation length clears the sense data." > + res = scsi_execute(sdp, cmd, DMA_NONE, NULL, 0, NULL, > + &my_sshdr, timeout, > + sdkp->max_retries, 0, RQF_PM, NULL); Only one level of retries please. Can sdkp->max_retries be changed into 1? Thanks, Bart.
On 6/28/21 6:34 AM, Martin Kepplinger wrote: > These cardreader device issues a MEDIA CHANGE unit attention not only > when actually a medium changed but also simply when resuming from suspend. > > Setting the BLIST_MEDIA_CHANGE flag enables using runtime pm for SD cardreaders. "device issues" -> "devices issue"? Anyway: Reviewed-by: Bart Van Assche <bvanassche@acm.org>
hi, (According to Alan Stern, "as far as I know, all") SD card readers send MEDIA_CHANGED unit attention notification on (runtime) resume. We cannot use runtime PM with these devices as I/O always fails in that case. This fixes runtime PM for SD cardreaders. I'd appreciate any feedback. To enable runtime PM for an SD cardreader 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 thank you, martin revision history ---------------- v4: (thank you Bart and Alan) * send SENSE REQUEST in sd instead of adding a global scsi error flag. v3: (thank you Bart) * create a new BLIST entry to mark affected devices instead of the sysfs module parameter for sd only. still, only sd implements handling the flag for now. * cc linux-pm list https://lore.kernel.org/linux-scsi/20210328102531.1114535-1-martin.kepplinger@puri.sm/ v2: https://lore.kernel.org/linux-scsi/20210112093329.3639-1-martin.kepplinger@puri.sm/ * move module parameter to sd * add Documentation v1: https://lore.kernel.org/linux-scsi/20210111152029.28426-1-martin.kepplinger@puri.sm/T/ For the full background, the discussion started in June 2020 here: https://lore.kernel.org/linux-scsi/20200623111018.31954-1-martin.kepplinger@puri.sm/ Martin Kepplinger (3): scsi: devinfo: add new flag BLIST_MEDIA_CHANGE scsi: sd: send REQUEST SENSE for BLIST_MEDIA_CHANGE devices in runtime_resume() scsi: devinfo: add BLIST_MEDIA_CHANGE for Ultra HS-SD/MMC usb cardreaders drivers/scsi/scsi_devinfo.c | 1 + drivers/scsi/sd.c | 37 ++++++++++++++++++++++++++++++++++++- include/scsi/scsi_devinfo.h | 6 +++--- 3 files changed, 40 insertions(+), 4 deletions(-)