Le 22/02/2016 08:03, Schrempf Frieder a écrit :
On 18.02.2016 18:14, Fabio Estevam wrote:
On Thu, Feb 18, 2016 at 1:32 PM, Marek Vasut marex@denx.de wrote:
Also one of our customers tested a few non-working sticks with this change and reported, that it fixed it for him. Here's a list of those devices, but I guess there are a lot more:
- Silicon Motion, Inc. - Taiwan (formerly Feiya Technology Corp.) Flash
Drive, VID: 0x090c, PID: 0x1000 2. Freecom Technologies, VID: 0x07ab, PID: 0xfcf1 3. Newron, VID: 0x8644, PID: 0x800e 4. GEMBIRD PhotoFrame PF-15-1, VID: 0x1908, PID: 0x1320
Maybe we need a quirk table then ?
It seems the list of affected devices is unknown.
What would be the impact of changing USB_MAX_XFER_BLK from 65535 to 32767?
Would this impact the USB transfer rate? Frieder, do you know?
I don't really know. While testing I had the feeling, that the transfer is slightly slower, but I can't tell for sure.
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.