Hi Marek, On 25 February 2016 at 10:56, Marek Vasut <ma...@denx.de> wrote: > On 02/25/2016 05:13 AM, Simon Glass wrote: >> Hi, >> >> On 24 February 2016 at 10:43, Marek Vasut <ma...@denx.de> wrote: >>> >>> On 02/23/2016 07:38 AM, Hannes Schmelzer wrote: >>>> On 22.02.2016 18:59, Fabio Estevam wrote: >>>>> On Mon, Feb 22, 2016 at 2:51 PM, Maxime Jayat <jayatmax...@gmail.com> >>>>> 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 ? >>> >>> We will probably need a quirk table and for the crappy USB sticks, we >>> will just have to use lower maximum xfer size. I would suggest to add >>> an environment variable, which would allow to override the max xfer >>> size. This would help in case the user had a device, which does need >>> a quirk, but is not yet in a quirk table ; as a temporary work around of >>> course. >> >> Yes. >> >> Even better if we can print a message telling the user about this when >> we detect this error. > > Agreed. Can you prepare such patch please ? >
Let me put it in my queue and think about it...no promises. Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
