Subject: usb host port3 on pxa310?

From: [email-masked] (David Hunter)
Date: Thu, 26 Aug 2010 12:28:59 -0700

On 8/22/2010 11:29 PM, Igor Grinberg wrote:
 >   On 08/22/10 11:20, Chen Wenjie wrote:
 >> and I found the VCC voltage is only 3.0v, it is lower than 3.3v
 >> (in the spec). Is this a fatal issue?
 >
 > May be not fatal, but could bring issues...
 > I'd check the VBUS on that usb port and also the pull ups on DP/DM.
 > If those are not by the spec. then the chances of getting it work are 
poor.

The host USB transceiver (ISP1105) should have external 15K pull-downs 
on both DP and DM. The device will have a pull-up on one signal to 
distinguish low speed vs. full speed.

You didn't mention what USB device you're test with. Is it actually full 
speed as the kernel logs indicate?

Do you mean VCC on ISP1105 is only 3.0V? That's the minimum, so it may 
still be functional. Hopefully the supply is adjustable.

ISP1105 supports both single-ended and differential input modes, as 
selected by the ISP1105's MODE pin. Can you confirm the PXA310 is set 
for the right mode? That'll be (digging thru the Dev Man) the P3SS bits 
in the U2DP3CR register in the U2D (Yes, the USB 2.0 Device Controller 
must be configured to use the USB Host Port 3. Thanks, Intel.) There's 
other important settings there, can't think of them off the top of my 
head. If that doesn't help, I'll share some code when my PXA310 box 
comes back online.

-Dave