From: Alan Stern <stern@rowland.harvard.edu>
To: Alexander Kappner <agk@godking.net>
Cc: Oliver Neukum <oneukum@suse.com>, <gregkh@linuxfoundation.org>,
<usb-storage@lists.one-eyed-alien.net>,
<linux-kernel@vger.kernel.org>, <linux-usb@vger.kernel.org>
Subject: Re: [PATCH] usb-storage: Add quirks to make G-Technology "G-Drive" work
Date: Fri, 18 May 2018 16:35:17 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1805181634000.1645-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <f12e75ed-206c-3cca-766c-447cd73b4280@godking.net>
On Fri, 18 May 2018, Alexander Kappner wrote:
> Further debugging shows that the code that causes the device to hang is in
> drivers/scsi/sd.c:2698. So the reason why usb-storage works and UAS does
> not is because the device setting both skip_ms_page_3f=1 and
> skip_ms_page_8=1 is required. The US_FL_NO_WP_DETECT flag does the former,
> and usb-storage (but not UAS) by default does the latter
> (drivers/usb/storage/scsiglue.c:198):
>
> /*
> * A number of devices have problems with MODE SENSE for
> * page x08, so we will skip it.
> */
> sdev->skip_ms_page_8 = 1;
>
>
> Forcing both skip_ms_page_3f and skip_ms_page_8 to 1 results in UAS and
> usb-storage working. Oliver's code only set skip_ms_page_3f.
Good detective work!
> Do we want a patch to introduce a quirk flag for skip_ms_page_8, similar to
> the US_FL_NO_WP_DETECT quirk bit for skip_ms_page_3f? This may even resolve
> the issues with other devices in unusual_uas.h that currently have all UAS
> support disabled. I'd be happy to write the patch, but I'm not sure we want
> to reserve a quirk bit for what's currently only a single device known to
> have this issue. Please advise.
Yes, I think we want a patch. Unless Oliver disagrees, please go ahead
and prepare one.
Alan Stern
next prev parent reply other threads:[~2018-05-18 20:35 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-16 20:01 [PATCH] usb-storage: Add quirks to make G-Technology "G-Drive" work Alexander Kappner
2018-05-16 20:55 ` Alan Stern
2018-05-17 8:15 ` Alexander Kappner
2018-05-17 12:58 ` Oliver Neukum
2018-05-17 18:38 ` Alexander Kappner
2018-05-17 19:13 ` Alan Stern
2018-05-18 17:51 ` Alexander Kappner
2018-05-18 20:35 ` Alan Stern [this message]
2018-05-19 4:50 ` [PATCH v2 0/2] " Alexander Kappner
2018-05-19 4:50 ` [PATCH v2 1/2] usb-storage: Add support for FL_ALWAYS_SYNC flag in the UAS driver Alexander Kappner
2018-05-22 8:58 ` [PATCH v2 1/2] [usb-storage] " Oliver Neukum
2018-05-19 4:50 ` [PATCH v2 2/2] usb-storage: Add compatibility quirk flags for G-Technologies G-Drive Alexander Kappner
2018-05-21 17:47 ` [PATCH v2 0/2] Re: usb-storage: Add quirks to make G-Technology "G-Drive" work Alan Stern
2018-05-22 8:57 ` [usb-storage] " Oliver Neukum
2018-05-17 14:44 ` [usb-storage] Re: [PATCH] " Alan Stern
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