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Date:   Thu, 13 Jun 2019 19:11:12 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Alan Stern <stern@rowland.harvard.edu>
Cc:     Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
        gregkh@linuxfoundation.org, hch@lst.de, linux-usb@vger.kernel.org,
        usb-storage@lists.one-eyed-alien.net,
        linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH v2] usb-storage: Add a limitation for
 blk_queue_max_hw_sectors()
Message-ID: <20190613171112.GA22155@lst.de>
References: <1560418611-10239-1-git-send-email-yoshihiro.shimoda.uh@renesas.com> <Pine.LNX.4.44L0.1906131258310.1307-100000@iolanthe.rowland.org>
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On Thu, Jun 13, 2019 at 01:06:40PM -0400, Alan Stern wrote:
> Hmmm.  Would it be easier instead to copy the DMA mapping parameters
> from us->pusb_dev->bus->sysdev into the SCSI host's parent before
> calling scsi_add_host()?  That way the correct values would be
> available from the beginning, so the existing DMA setup would
> automatically use the correct sizes.

It would in theory.  But at usb-storage has a special max_sectors quirk
for tape devices, and as the device type is a per-LU property we'd
still have to override it in ->slave_configure.