diff mbox series

[v5,2/3] scsi: sd: send REQUEST SENSE for BLIST_MEDIA_CHANGE devices in runtime_resume()

Message ID 20210630084453.186764-3-martin.kepplinger@puri.sm
State Superseded
Headers show
Series fix runtime PM for SD card readers | expand

Commit Message

Martin Kepplinger June 30, 2021, 8:44 a.m. UTC
For SD cardreader devices that have the BLIST_MEDIA_CHANGE flag set,
a MEDIA CHANGE unit attention is received after resuming from runtime
suspend. Send a REQUEST SENSE to avoid that.

The "downside" is that for these devices we now rely on users not to
really 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

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
---
 drivers/scsi/sd.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

Comments

Bart Van Assche July 1, 2021, 2:35 p.m. UTC | #1
On 6/30/21 1:44 AM, Martin Kepplinger wrote:
> For SD cardreader devices that have the BLIST_MEDIA_CHANGE flag set,

> a MEDIA CHANGE unit attention is received after resuming from runtime

> suspend. Send a REQUEST SENSE to avoid that.


Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Martin Kepplinger July 2, 2021, 8:04 a.m. UTC | #2
Am Donnerstag, dem 01.07.2021 um 15:49 +0100 schrieb Christoph Hellwig:
> On Wed, Jun 30, 2021 at 10:44:52AM +0200, Martin Kepplinger wrote:

> > +       struct scsi_disk *sdkp = dev_get_drvdata(dev);

> > +       struct scsi_device *sdp = sdkp->device;

> > +       int timeout, res;

> > +

> > +       timeout = sdp->request_queue->rq_timeout *

> > SD_FLUSH_TIMEOUT_MULTIPLIER;

> 

> Is REQUEST SENSE reqlly a so slow operation on these devices that

> we need to override the timeout?


using SD_TIMEOUT works equally fine for me. Is that what you'd rather
like to see?

Bart, is SD_TIMEOUT equally ok for you? If so, I'll resend with your
reviewed-by.

thank you for reviewing!

                            martin
Bart Van Assche July 2, 2021, 1:43 p.m. UTC | #3
On 7/2/21 1:04 AM, Martin Kepplinger wrote:
> Am Donnerstag, dem 01.07.2021 um 15:49 +0100 schrieb Christoph Hellwig:

>> On Wed, Jun 30, 2021 at 10:44:52AM +0200, Martin Kepplinger wrote:

>>> +       struct scsi_disk *sdkp = dev_get_drvdata(dev);

>>> +       struct scsi_device *sdp = sdkp->device;

>>> +       int timeout, res;

>>> +

>>> +       timeout = sdp->request_queue->rq_timeout *

>>> SD_FLUSH_TIMEOUT_MULTIPLIER;

>>

>> Is REQUEST SENSE reqlly a so slow operation on these devices that

>> we need to override the timeout?

> 

> using SD_TIMEOUT works equally fine for me. Is that what you'd rather

> like to see?

> 

> Bart, is SD_TIMEOUT equally ok for you? If so, I'll resend with your

> reviewed-by.


Hi Martin,

I prefer sdp->request_queue->rq_timeout instead of SD_TIMEOUT since the 
former is configurable via sysfs.

Thanks,

Bart.
diff mbox series

Patch

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 6d2d63629a90..b02378f40620 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -63,6 +63,7 @@ 
 #include <scsi/scsi_cmnd.h>
 #include <scsi/scsi_dbg.h>
 #include <scsi/scsi_device.h>
+#include <scsi/scsi_devinfo.h>
 #include <scsi/scsi_driver.h>
 #include <scsi/scsi_eh.h>
 #include <scsi/scsi_host.h>
@@ -114,6 +115,7 @@  static void sd_shutdown(struct device *);
 static int sd_suspend_system(struct device *);
 static int sd_suspend_runtime(struct device *);
 static int sd_resume(struct device *);
+static int sd_resume_runtime(struct device *);
 static void sd_rescan(struct device *);
 static blk_status_t sd_init_command(struct scsi_cmnd *SCpnt);
 static void sd_uninit_command(struct scsi_cmnd *SCpnt);
@@ -608,7 +610,7 @@  static const struct dev_pm_ops sd_pm_ops = {
 	.poweroff		= sd_suspend_system,
 	.restore		= sd_resume,
 	.runtime_suspend	= sd_suspend_runtime,
-	.runtime_resume		= sd_resume,
+	.runtime_resume		= sd_resume_runtime,
 };
 
 static struct scsi_driver sd_template = {
@@ -3720,6 +3722,28 @@  static int sd_resume(struct device *dev)
 	return ret;
 }
 
+static int sd_resume_runtime(struct device *dev)
+{
+	struct scsi_disk *sdkp = dev_get_drvdata(dev);
+	struct scsi_device *sdp = sdkp->device;
+	int timeout, res;
+
+	timeout = sdp->request_queue->rq_timeout * SD_FLUSH_TIMEOUT_MULTIPLIER;
+
+	if (sdp->sdev_bflags & BLIST_MEDIA_CHANGE) {
+		/* clear the devices' sense data */
+		static const u8 cmd[10] = { REQUEST_SENSE };
+
+		res = scsi_execute(sdp, cmd, DMA_NONE, NULL, 0, NULL,
+				   NULL, timeout, 1, 0, RQF_PM, NULL);
+		if (res)
+			sd_printk(KERN_NOTICE, sdkp,
+				  "Failed to clear sense data\n");
+	}
+
+	return sd_resume(dev);
+}
+
 /**
  *	init_sd - entry point for this driver (both when built in or when
  *	a module).