On Fri, 11 Mar 2005, peng peng wrote:
> HI,
>
> I use the following code to enable portsc of uhci
> under DOS,but the port enable failed (set the bit but
> it doesn`t take effect) , I don't know why . Is there
> anyone know what's the problem ? Thanks :)
>
>
> static void uhci_reset_port(unsigned int port)
> {
> unsigned short status;
>
> status = inw(port);
> outw(status | USBPORTSC_PR, port); /* reset port */
You should be more careful not to write out bits that are R/WC.
> wait_ms(10);
This delay should be 50 ms according to the USB 2.0 spec.
> outw(status & ~USBPORTSC_PR, port);
> udelay(5);
>
> status = inw(port);
> outw(status | USBPORTSC_PE, port); /* enable port */
> wait_ms(10);
You will probably need to clear USBPORTSC_PEC and USBPORTSC_CSC.
> status = inw(port);
> if(!(status & USBPORTSC_PE)) {
> outw(status | USBPORTSC_PE, port); /* one more try
> at enabling port */
> wait_ms(50);
> }
Keep in mind that setting the port-enable bit won't work if the port is
not connected.
Alan Stern
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