I believe we have found a real solution to this problem. Please try it
out and post your results so we can verify how well it works. We found
two issues which seem to contribute to this problem:
1) The EHCI controller has a setting for number of retries (1, 2, 3, or
endless). The kernel sets it to 3. Try setting it to 0 (endless retries).
This setting is in drivers/usb/host/ehci-hcd.c, line 107:
#define EHCI_TUNE_CERR 3 /* 0-3 qtd retries; 0 == don't
stop */
Simply change the 3 to a 0. This will cause it to retry failed transactions
endlessly until they succeed. I don't know if this will have an adverse effect
on non-mass storage devices (the only USB devices we have in our system are
flash drives).
2) The BIOS may not be setting the Frame Length Adjustment register.
This one is a little more obscure. See page 10 of the EHCI
specification, available on Intel's web site. Our motherboard (ECS
P4M800PRO-M478) is not setting a value for this register. ECS seemed to
not know what we were talking about when we asked about it. The kernel
should not have to set this but it can, by inserting the following code
into the top of ehci_pci_setup() in drivers/usb/host/ehci-pci.c (about
line 74):
{
u8
fladj;
pci_read_config_byte(pdev,0x61,&fladj);
printk("FLADJ was=%02X\n",fladj);
pci_write_config_byte(pdev,0x61,0x00);
pci_read_config_byte(pdev,0x61,&fladj);
printk("FLADJ is now=%02X\n",fladj);
}
The FLADJ register's address is 0x61. This will set the value to 0x00
(worked well for us, may be totally wrong for you). Since this is a
function of the specific motherboard you'll probably have to find the
right number empirically. You can verify if your motherboard is writing
its own value by booting once to set your value then rebooting (without
powering off) and noting if the "was=" in the logs is what you
previously set or if it's something different. If it's different then
the BIOS wrote to it and probably knows the correct value and you should
leave this alone. The valid range is 0x00 through 0x3F. The default is
0x20.
Build the kernel in your usual fashion, give it a spin, and let me know
how it goes. I hope this helps.
-Andrew
--
USB mass storage stops working after a while
https://bugs.launchpad.net/bugs/61235
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