Date: Mon, 09 Feb 2015 22:26:42 +0100 From: Hans Petter Selasky <hps@selasky.org> To: gljennjohn@gmail.com, usb@freebsd.org, John Baldwin <jhb@freebsd.org> Subject: Re: r276717 causes problems Message-ID: <54D92612.6000207@selasky.org> In-Reply-To: <20150209183648.7825eee5@ernst.home> References: <20150209183648.7825eee5@ernst.home>
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Hi John, Do all PCI busses support 64-bit DMA busmaster? Do we reflect this in the busdma tags passed down to device drivers? --HPS On 02/09/15 18:36, Gary Jennejohn wrote: > r276717 breaks access to my 4-disk external USB3 (XHCI) enclosure. > > The symptom is that only the first of the threee disks is found. > > r276716 sees all the disks immediately. > > This is the output for the bridge chip: > > umass0: <JMicron USB to ATAATAPI Bridge, class 0/0, rev 3.00/28.03, addr 2> on usbus0 > > The problem seems to be mainly due to setting dma_bits to 64. It's > true that the chip on the controller board supports 64 bit DMA, but the > JMicron seems to have a real crisis when that setting is used, although > I don't know why. > > Note that the nice output above was obtained after hard coding dma_bits > to 32 in xhci_init(). With 64 bits I see this: > > umass0: <vendor 0x152d product 0x0539, class 0/0, rev 3.00/28.03, addr 3> on usbus0 > > probably because reading the strings from the device fails. > > Anyway, it would be nice to have a sysctl to force dma_bits to 32. > > Unfortunately, I still have a problem with my enclosure with more > current versions of HEAD. The rather questionable practice of > always doing a multi LUN enquiry using the SCSI-3 CDB byte 0xa0 > also causes problems. Considering that most of these bridge > chips can barely emulate SCSI-2 it seems rather foolish to try to > jam SCSI-3 CDB bytes down their throats. > > But that's a different story. >
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