From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Schmelzer Date: Tue, 23 Feb 2016 07:38:35 +0100 Subject: [U-Boot] Issue with USB mass storage (thumb drives) In-Reply-To: References: <56B08683.9000607@exceet.de> <56B309F3.9000503@exceet.de> <201602041228.53313.marex@denx.de> <56C5974E.10600@exceet.de> <56C5E3F5.4040906@denx.de> <56CAB2C8.8040703@exceet.de> <56CB4ABD.2090900@gmail.com> Message-ID: <56CBFE6B.2040708@schmelzer.or.at> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 22.02.2016 18:59, Fabio Estevam wrote: > On Mon, Feb 22, 2016 at 2:51 PM, Maxime Jayat wrote: > >> Hello, >> I was hit by the same problem, where my USB SD card reader would timeout >> in U-boot when reading a large file (16 MB). Changing USB_MAX_XFER_BLK >> to 32767 fixed the problem but I investigated a little more. >> I was curious to see what the Linux kernel used, because it had no >> problem reading the file. In Linux, USB_MAX_XFER_BLK corresponds to >> max_sector in the scsiglue, which is set to 240 blocks per transfer by >> default, and is tunable via sysfs. >> There is also a list of unusual devices which needs no higher than 64 >> blocks per transfer. >> The linux USB FAQ has a very interesting entry about this which explains >> the rationale for this value: >> http://www.linux-usb.org/FAQ.html#i5 >> >> FWIW: my USB card reader is >> 0bda:0119 Realtek Semiconductor Corp. Storage Device (SD card reader) >> >> I've benchmarked in U-boot the time impact of this change. >> For reading my 16764395 bytes file: >> USB_MAX_XFER_BLK Read duration (as reported by U-boot): >> 64 3578 ms >> 128 2221 ms >> 240 1673 ms >> 32767 1020 ms >> 65535 974 ms >> >> So there is definitely a strong impact for lower values. > Ok, so with a USB_MAX_XFER_BLK size of 32767 there is not so much of a > performance impact. > > Looks like that changing USB_MAX_XFER_BLK from 65535 to 32767 is the way to go. I have configured a value of 8191 some few weeks ago on my zynq board, there was no negative feedback until yesterday :-( A colleague of mine told me, that his USB-stick doesn't work. I had a look. Vendor: 0x1307 Product 0x0165 Version 1.0 I had to reduce the USB_MAX_XFER_BLK downto 2048 to make it work. I'm not the big usb-expert ... but would it be possible to move away from this #define to some variable which is adapted to the lowest value on the bus. Is it possible at all to get to right value out of some register ? regards, Hannes