Re: Test Patch: 2.5.69 Interrupt Latency

Paul Fulghum (paulkf@microgate.com)
15 May 2003 09:12:37 -0500


I have a question about the wakeup_hc() code in general:

when waking in response to a resume event,
the current code sets the USBCMD_FGR (force global resume)
and USBCMD_EGSM (enter global suspend mode) bits,
waits 20ms and clears both bits to start sending EOP signal.

According to the datasheet, the controller itself
(not software) sets the FGR bit on detection of
a resume event. 20ms after the USBSTS_RD indication,
software should clear both the FGR and EGSM bits.

My reading of this is that the line:

outw(USBCMD_FGR | USBCMD_EGSM, io_addr + USBCMD);

before the 20ms wait should not be necessary.

Am I reading this correctly?

Thanks,
Paul

-- 
Paul Fulghum, paulkf@microgate.com
Microgate Corporation, http://www.microgate.com

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