Re: [9fans] question on implementation of uhci host controller driver

[Lonnie Mendez <lmendez19@austin.rr.com>]

Charles Forsyth wrote:

>> If the initial value isn't the default
>>value then I'll be understanding this a whole lot better.
>>
>>
>
>yes, having checked the spec again i see what you mean.
>i'm not sure, then.  if i have a spare moment when working on the ohci
>i'll see what is in the uhci registers after a reset.
>
    I added a debug statement to show the initial value set in the uhci
probe function under linux.  This is displayed before the hcd ever
touches the registers:

uhci_hcd 0000:00:1d.0: UHCI Host Controller
uhci_hcd 0000:00:1d.0: detected 2 ports
uhci_hcd 0000:00:1d.0: uhci_check_and_reset_hc: sts = 0x0020
uhci_hcd 0000:00:1d.0: uhci_check_and_reset_hc: cmd = 0x0000

   Sure enough the status register has hchalted bit set.  I'm not sure
if the bios does this or the firmware on the uhci controller.  I'll
submit a patch for qemu to make it more realistic (and so plan9 boots
with -usb parameter).

Most of my patches for qemu are linked here:
http://gnome.dnsalias.net/patches/