Hi,
I'm running linux 2.6.11 (vanilla) on a custom board, with a
Sharp LH7A404.
.config:
CONFIG_ARCH_LH7A40X=y
CONFIG_ARCH_LH7A404=y
I've been having problems with a USB storage chip connected to the
USB host interface (ST72F65, soldered on to the board).
To detect media presence, I have a program that polls /dev/sd[abcde]
once every 2 seconds or so, and reads a sector's worth of data, roughly
equivalent to,
$ dd if=/dev/sdc of=/dev/null bs=512 count=1 \
&& echo 'Media present' || echo 'No media'
Way down, this calls, from drivers/usb/host/ohci.h:
static u32 roothub_portstatus (struct ohci_hcd *hc, int i)
{ return read_roothub (hc, portstatus [i], 0xffe0fce0); }
and typically this returns 0x103,
00000100=RH_PS_PPS (port power status)
00000002=RH_PS_PES (port enable status)
00000001=RH_PS_CCS (current connect status)
but after a minute or two of polling (once a second or so), I get 0x30101,
00020000=RH_PS_PESC (port enable status change)
00010000=RH_PS_CSC (connect status change)
00000100=RH_PS_PPS (port power status)
00000001=RH_PS_CCS (current connect status)
which bubbles up through the calling code in the usb layer and triggers
a disconnect cycle due to PESC and CSC,
ohci_hub_status_data (struct usb_hcd *hcd, char *buf)
{
...
for (i = 0; i < ports; i++) {
u32 status = roothub_portstatus (ohci, i);
if (status & (RH_PS_CSC | RH_PS_PESC | RH_PS_PSSC
| RH_PS_OCIC | RH_PS_PRSC)) {
changed = 1;
Now my questions:
1) Is there a better way to poll for media presence than reading
/dev/sd[a..e] ?
2) Does the 0x30101 look like a sane response? I'm seeing 0x30100
when I remove an IOGEAR media reader connected through via a
standard USB TypeA port.
Any other insights/tips are welcome.
This might come down to a board-layout or electrical problem, I know.
Thanks,
-Jamie
p.s. I got the 0x30101/etc numbers by saving the result of
roothub_portstatus() in a huge buffer in the kernel, then downloading
the buffer through a /proc file. Its an embarassingly ugly hack, but
it was the only way I could avoid messing with USB timing.
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