Re: [PATCH] Fix OTG HNP for hub.c (USB OTG HNP (can you find any other appropriate TLAs?)
Tony Lindgren <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
* David Brownell <[email protected]> [070529 16:04]: > On Tuesday 29 May 2007, Tony Lindgren wrote: > > > I see your point though with "autoidle", but that's after > > the devices have enumerated the wrong way, right? > > You want me to look at that code again? Aargh! > > Originally there was no autoidle, so the logic was: > the only way Linux will *EVER* trigger suspend at > runtime was to try HNP. Devices that don't pass the > whitelist test would enumerate no further. > > Now we have working auto-idle, so other logic could > be applied. I think you're suggesting that maybe > they could proceed through enumeration, fail that, > and then autosuspend to trigger HNP ... ? That might > be workable. Sorry, in my snip frenzy I forgot to reply to some parts:) Yes, well I'll see what happens with OPT and post some results. > The behavioral difference would be that WHEN ("not 'IF'") > the whitelist (which is very easily checked against product > documentation) diverges from the list of configured drivers > (no easy way to crosscheck that and docs) things would not > act the same. I guess HNP should be offered for peripherals even if not on whitelist, but only peripherals on whitelist (with HNP or not) should be allowed. > This is more or less what you were trying to achieve, > yes? But it leads to surprising behavior in cases > like: > > * hook up non-OTG peripheral #1 ... acts just > the way you'd normally expect > > * hook up OTG peripheral #2 ... surprise! it > refuses to act as a peripheral at first. > > The "principle of least astonishment" argues that > the "peripheral #1" model should be followed for > as long as possible. Customer service calls would > be a lot simpler too... Yeh I guess in that case it needs to wait for autosuspend until #1 is done. But if #2 is not on whitelist and can do HNP, then it just gets rejected and never gets it's HNP opportunity. Hmmm... Tony ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel