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From: Alan Stern <stern@rowland.harvard.edu>
To: Christoph Hellwig <hch@lst.de>, Hans de Goede <hdegoede@redhat.com>
Cc: Tom Yan <tom.ty89@gmail.com>,
	linux-usb <linux-usb@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	SCSI development list <linux-scsi@vger.kernel.org>
Subject: Re: [PATCH 2/2] usb-storage: revert from scsi_add_host_with_dma() to scsi_add_host()
Date: Mon, 1 Mar 2021 10:59:27 -0500	[thread overview]
Message-ID: <20210301155927.GB1490228@rowland.harvard.edu> (raw)
In-Reply-To: <20210226055352.GA2996@lst.de>

On Fri, Feb 26, 2021 at 06:53:52AM +0100, Christoph Hellwig wrote:
> On Thu, Feb 25, 2021 at 11:35:57AM -0500, Alan Stern wrote:
> > This thread seems to have fallen through the cracks.  Maybe now would be 
> > a good time to address the problem (since we originally planned to fix 
> > it in 5.11!).
> > 
> > The questions listed below are pretty self-contained, although the rest
> > of the discussion isn't.  But I never received any answers.
> 
> usb-storage must use scsi_add_host_with_dma to use the right device
> for DMA mapping and parameters.  The calls to set the DMA options
> on the device are needed so that IOMMU merging doesn't change the
> imposed requirements.  If these requirements slow you down you need
> to relax them, as apparently the hardware is able to handle bigger
> limits.

Hans, don't you have the right equipment to test this approach?

Alan Stern

  reply	other threads:[~2021-03-01 16:00 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-10 11:36 5.10 regression, many XHCI swiotlb buffer is full / DMAR: Device bounce map failed errors on thunderbolt connected XHCI controller Hans de Goede
2020-11-18 21:43 ` Hans de Goede
2020-11-23 14:49 ` Hans de Goede
2020-11-24 10:27   ` Christoph Hellwig
2020-11-24 10:31     ` Hans de Goede
2020-11-24 12:17       ` Mathias Nyman
2020-11-27 11:41     ` Hans de Goede
2020-11-27 12:32       ` 5.10 regression caused by: "uas: fix sdev->host->dma_dev": " Hans de Goede
2020-11-27 16:19         ` Christoph Hellwig
2020-11-27 18:12           ` Hans de Goede
2020-11-28  1:25             ` Tom Yan
2020-11-28 10:43               ` Hans de Goede
2020-11-28 15:48                 ` [PATCH 1/2] uas: revert from scsi_add_host_with_dma() to scsi_add_host() Tom Yan
2020-11-28 15:48                   ` [PATCH 2/2] usb-storage: " Tom Yan
2020-11-30  9:50                     ` Hans de Goede
2020-11-30 12:58                       ` Tom Yan
2020-11-30 13:23                         ` Hans de Goede
2020-11-30 13:30                           ` Greg KH
2020-11-30 13:36                             ` Hans de Goede
2020-11-30 13:53                               ` Greg KH
2020-11-30 13:55                                 ` Hans de Goede
2020-12-04 15:02                                   ` Greg KH
2020-11-30 17:20                               ` Alan Stern
2020-11-30 17:24                                 ` Christoph Hellwig
2020-11-30 18:18                                 ` Hans de Goede
2020-11-30 18:57                                   ` Tom Yan
2020-11-30 19:01                                     ` Tom Yan
2020-11-30 20:36                                       ` Alan Stern
2021-02-25 16:35                                         ` Alan Stern
2021-02-26  5:53                                           ` Christoph Hellwig
2021-03-01 15:59                                             ` Alan Stern [this message]
2020-11-30 14:39                           ` Tom Yan
2020-11-30  9:48                   ` [PATCH 1/2] uas: " Hans de Goede
2020-11-30 19:30                     ` Tom Yan
2020-12-01 11:09                       ` Hans de Goede
2020-11-28 17:15             ` 5.10 regression caused by: "uas: fix sdev->host->dma_dev": many XHCI swiotlb buffer is full / DMAR: Device bounce map failed errors on thunderbolt connected XHCI controller Christoph Hellwig
2020-11-30  8:43               ` Hans de Goede

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