Re: Re: another must-fix: major PS/2 mouse problem

Chris Friesen <[email protected]>
Newsgroups gmane.linux.drivers.vortex.devel
Message-ID <[email protected]>
Donald Becker wrote:
> On Tue, 29 Jul 2003, Chris Friesen wrote:

>>You might want to bump that up a little bit.  Querying carrier signal on 
>>a tulip chip is 100usecs with interrupts off.

> My drivers, include the Tulip, don't read serial MII registers in the
> interrupt service during noraml operation.  That would be a Very Bad
> Thing.  (Exception: for a few chips there is a check in the rare case
> that the link changes during active operation.)
> 
> Serial MII management operations should only be done during timer ticks
> and user-level ioctl() operations.

Yep, this is from user-level. Basically we were querying the driver 
through ioctl() to check whether the card has carrier or not.  The board 
manufacturer didn't bother hooking up the interrupt line on the phy so 
we had to poll the phy for carrier loss detection.  As part of the 
ioctl() the normal code turned off interrupts while doing the MII stuff.

We didn't like that very much, so I made use of the fact that the clock 
pulse for the MII connection was user-driven (and hence not 
timing-sensitive) to allow interrupts to be on while querying the 
carrier.  Seems to work fine.

Chris


-- 
Chris Friesen                    | MailStop: 043/33/F10
Nortel Networks                  | work: (613) 765-0557
3500 Carling Avenue              | fax:  (613) 765-2986
Nepean, ON K2H 8E9 Canada        | email: [email protected]

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