From: Christoph Hellwig <hch@lst.de>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Greg KH <greg@kroah.com>,
Piergiorgio Sartor <piergiorgio.sartor@nexgo.de>,
Seth Bollinger <Seth.Bollinger@digi.com>,
Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
USB list <linux-usb@vger.kernel.org>
Subject: Re: [PATCH] usb-storage: Revert commit 747668dbc061 ("usb-storage: Set virt_boundary_mask to avoid SG overflows")
Date: Wed, 23 Oct 2019 03:53:48 +0200 [thread overview]
Message-ID: <20191023015348.GA16123@lst.de> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1910211145520.1673-100000@iolanthe.rowland.org>
On Mon, Oct 21, 2019 at 11:48:06AM -0400, Alan Stern wrote:
> There is no longer any reason to keep the virt_boundary_mask setting
> for usb-storage. It was needed in the first place only for handling
> devices with a block size smaller than the maxpacket size and where
> the host controller was not capable of fully general scatter-gather
> operation (that is, able to merge two SG segments into a single USB
> packet). But:
>
> High-speed or slower connections never use a bulk maxpacket
> value larger than 512;
>
> The SCSI layer does not handle block devices with a block size
> smaller than 512 bytes;
>
> All the host controllers capable of SuperSpeed operation can
> handle fully general SG;
>
> Since commit ea44d190764b ("usbip: Implement SG support to
> vhci-hcd and stub driver") was merged, the USB/IP driver can
> also handle SG.
>
> Therefore all supported device/controller combinations should be okay
> with no need for any special virt_boundary_mask. So in order to fix
> the swiotlb problem, this patch reverts commit 747668dbc061.
That's great to know. The same should also apply to uas, shouldn't
it?
Otherwise:
Acked-by: Christoph Hellwig <hch@lst.de>
next prev parent reply other threads:[~2019-10-23 1:53 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-17 9:54 reeze while write on external usb 3.0 hard disk [Bug 204095] Piergiorgio Sartor
2019-08-19 14:14 ` Alan Stern
2019-08-20 7:23 ` Christoph Hellwig
2019-08-20 16:37 ` Piergiorgio Sartor
2019-08-26 17:38 ` Piergiorgio Sartor
2019-08-29 14:08 ` Christoph Hellwig
2019-09-25 17:07 ` Piergiorgio Sartor
2019-09-25 18:31 ` Alan Stern
2019-09-27 9:04 ` Peter Chen
2019-09-29 20:13 ` Piergiorgio Sartor
2019-09-30 1:01 ` Alan Stern
2019-09-30 18:25 ` Piergiorgio Sartor
2019-10-13 18:11 ` Piergiorgio Sartor
2019-10-16 17:01 ` Alan Stern
2019-10-17 17:53 ` Piergiorgio Sartor
2019-10-17 19:23 ` Alan Stern
2019-11-08 23:05 ` Piergiorgio Sartor
2019-10-21 15:48 ` [PATCH] usb-storage: Revert commit 747668dbc061 ("usb-storage: Set virt_boundary_mask to avoid SG overflows") Alan Stern
2019-10-23 1:53 ` Christoph Hellwig [this message]
2019-10-23 14:12 ` Alan Stern
2019-10-23 15:34 ` [PATCH] UAS: Revert commit 3ae62a42090f ("UAS: fix alignment of scatter/gather segments") Alan Stern
2019-10-24 1:10 ` Christoph Hellwig
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