From: Martin Kepplinger <martin.kepplinger@puri.sm>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>,
Bart Van Assche <bvanassche@acm.org>,
Can Guo <cang@codeaurora.org>,
martin.petersen@oracle.com, linux-scsi@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel@puri.sm
Subject: Re: [PATCH] scsi: sd: add runtime pm to open / release
Date: Tue, 4 Aug 2020 11:39:59 +0200 [thread overview]
Message-ID: <9b80ca7c-39f8-e52d-2535-8b0baf93c7d1@puri.sm> (raw)
In-Reply-To: <20200730151030.GB6332@rowland.harvard.edu>
On 30.07.20 17:10, Alan Stern wrote:
> On Thu, Jul 30, 2020 at 10:52:14AM +0200, Martin Kepplinger wrote:
>> Maybe I should just start a new discussion with a patch, but the below
>> is what makes sense to me (when I understand you correctly) and seems to
>> work. I basically add a new flag, so that the old flags behave unchanged
>> and only call it during *runtime* resume for SD cards:
>>
>>
>> --- a/drivers/scsi/scsi_error.c
>> +++ b/drivers/scsi/scsi_error.c
>> @@ -553,15 +553,21 @@ int scsi_check_sense(struct scsi_cmnd *scmd)
>> * information that we should pass up to the upper-level
>> driver
>> * so that we can deal with it there.
>> */
>> - if (scmd->device->expecting_cc_ua) {
>> + if (scmd->device->expecting_cc_ua ||
>> + scmd->device->expecting_media_change) {
>> /*
>> * Because some device does not queue unit
>> * attentions correctly, we carefully check
>> * additional sense code and qualifier so as
>> - * not to squash media change unit attention.
>> + * not to squash media change unit attention;
>> + * unless expecting_media_change is set, indicating
>> + * that the media (most likely) didn't change
>> + * but a device only believes so (for example
>> + * because of suspend/resume).
>> */
>> - if (sshdr.asc != 0x28 || sshdr.ascq != 0x00) {
>> - scmd->device->expecting_cc_ua = 0;
>> + if ((sshdr.asc != 0x28 || sshdr.ascq != 0x00) ||
>> + scmd->device->expecting_media_change) {
>> + scmd->device->expecting_media_change = 0;
>> return NEEDS_RETRY;
>> }
>> }
>> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
>> index d90fefffe31b..b647fab2b663 100644
>> --- a/drivers/scsi/sd.c
>> +++ b/drivers/scsi/sd.c
>> @@ -114,6 +114,7 @@ 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);
>> @@ -574,7 +575,7 @@ 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 = {
>> @@ -3652,6 +3653,21 @@ 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);
>> +
>> + /* Some SD cardreaders report media change when resuming from
>> suspend
>> + * because they can't keep track during suspend. */
>> +
>> + /* XXX This is not unproblematic though: We won't notice when a card
>> + * was really changed during runtime suspend! We basically rely
>> on users
>> + * to unmount or suspend before doing so. */
>> + sdkp->device->expecting_media_change = 1;
>> +
>> + return sd_resume(dev);
>> +}
>> +
>> /**
>> * init_sd - entry point for this driver (both when built in or when
>> * a module).
>> diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
>> index bc5909033d13..8c8f053f71c8 100644
>> --- a/include/scsi/scsi_device.h
>> +++ b/include/scsi/scsi_device.h
>> @@ -169,6 +169,8 @@ struct scsi_device {
>> * this device */
>> unsigned expecting_cc_ua:1; /* Expecting a CHECK_CONDITION/UNIT_ATTN
>> * because we did a bus reset. */
>> + unsigned expecting_media_change:1; /* Expecting media change
>> ASC/ASCQ
>> + when it actually doesn't
>> change */
>> unsigned use_10_for_rw:1; /* first try 10-byte read / write */
>> unsigned use_10_for_ms:1; /* first try 10-byte mode sense/select */
>> unsigned set_dbd_for_ms:1; /* Set "DBD" field in mode sense */
>
> That's pretty much what James was suggesting, except for one thing: You
> must not set sdkp->device->expecting_media_change to 1 for all devices
> in sd_runtime_resume(). Only for devices which may generate a spurious
> Unit Attention following runtime resume -- and maybe not even for all of
> them, depending on what the user wants.
>
> Alan Stern
>
when I mount the SD card myself or via Nautilus, things work. When I put
sth like:
/dev/sda1 /mnt/sda1 auto auto,nofail 0 2
into fstab, I *still* get (constantly) when accessing the files:
[ 50.838061] sd 0:0:0:0: [sda] tag#0 device offline or changed
why could that be? is there another place we would add such a new flag
(not only resume())?
martin
next prev parent reply other threads:[~2020-08-04 9:40 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 11:10 [PATCH] scsi: sd: add runtime pm to open / release Martin Kepplinger
2020-06-24 13:33 ` Bart Van Assche
2020-06-25 8:16 ` Martin Kepplinger
2020-06-25 14:52 ` Alan Stern
2020-06-26 3:53 ` Bart Van Assche
2020-06-26 15:07 ` Bart Van Assche
2020-06-26 15:44 ` Alan Stern
2020-06-28 2:37 ` Bart Van Assche
2020-06-28 13:10 ` Alan Stern
2020-06-29 9:42 ` Martin Kepplinger
2020-06-29 16:15 ` Alan Stern
2020-06-29 16:56 ` Bart Van Assche
2020-06-29 17:40 ` Alan Stern
2020-06-30 3:33 ` Martin Kepplinger
2020-06-30 13:38 ` Alan Stern
2020-06-30 15:59 ` Bart Van Assche
2020-06-30 18:02 ` Alan Stern
2020-06-30 19:23 ` Bart Van Assche
2020-06-30 19:38 ` Alan Stern
2020-06-30 23:31 ` Bart Van Assche
2020-07-01 0:49 ` Alan Stern
2020-07-06 16:41 ` Alan Stern
2020-07-28 7:02 ` Martin Kepplinger
2020-07-28 20:02 ` Alan Stern
2020-07-29 14:12 ` Martin Kepplinger
2020-07-29 14:32 ` Alan Stern
2020-07-29 14:44 ` Martin K. Petersen
2020-07-29 14:56 ` Alan Stern
2020-07-29 14:46 ` James Bottomley
2020-07-29 14:53 ` James Bottomley
2020-07-29 15:40 ` Martin Kepplinger
2020-07-29 15:44 ` James Bottomley
2020-07-29 16:43 ` Martin Kepplinger
2020-07-29 18:25 ` Alan Stern
2020-07-29 18:29 ` James Bottomley
2020-07-30 8:52 ` Martin Kepplinger
2020-07-30 8:54 ` Martin Kepplinger
2020-07-30 15:10 ` Alan Stern
2020-08-04 9:39 ` Martin Kepplinger [this message]
2020-08-07 9:51 ` Martin Kepplinger
2020-08-07 14:30 ` Alan Stern
2020-08-08 6:59 ` Martin Kepplinger
2020-08-08 15:05 ` Alan Stern
2020-08-09 9:20 ` Martin Kepplinger
2020-08-09 15:26 ` Alan Stern
2020-08-10 12:03 ` Martin Kepplinger
2020-08-10 14:13 ` Alan Stern
2020-08-11 7:55 ` Martin Kepplinger
2020-08-11 13:48 ` Alan Stern
2020-07-29 15:40 ` Alan Stern
2020-07-29 15:49 ` James Bottomley
2020-07-29 16:17 ` Alan Stern
2020-07-29 15:52 ` Martin Kepplinger
2020-07-29 18:10 ` Douglas Gilbert
2020-07-30 8:05 ` Martin Kepplinger
2020-07-30 15:14 ` Alan Stern
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