Date: Wed, 13 Apr 2011 17:22:37 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Nick Hibma <nick@van-laarhoven.org> Cc: =?windows-1252?Q?Current_Mailing_List=93?= <freebsd-current@FreeBSD.org>, =?windows-1252?Q?=93FreeBSD_USB_Mailing_List=93?= <freebsd-usb@FreeBSD.org>, =?windows-1252?Q?=93FreeBSD_?=, Hans Petter Selasky <hselasky@c2i.net> Subject: Re: use_generic and usb probing Message-ID: <4DA5B1AD.5070703@FreeBSD.org> In-Reply-To: <87909196-8EAB-4255-A1C7-6AAB22FA46E8@van-laarhoven.org> References: <201104051321.56319.hselasky@freebsd.org> <4D9B1023.7020407@FreeBSD.org> <201104051455.33853.hselasky@freebsd.org> <4D9B473F.8020607@FreeBSD.org> <87909196-8EAB-4255-A1C7-6AAB22FA46E8@van-laarhoven.org>
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on 13/04/2011 00:48 Nick Hibma said the following: >> Well, I think that that's what probe priorities actually for. I also think >> that typically ivars should be set by a bus driver. So maybe it's not such a >> good idea to pass data from probe to attach via ivars in child drivers. But I >> could be mistaken about that. >> >> Practically speaking, you most likely don't have to worry about that for >> drivers that return BUS_PROBE_SPECIFIC (=0) from their probe methods. And >> there is only a few "generic" drivers that can be handled on a case by case >> basis. > > Newbus priorities where specifically implemented on my request by Doug Rabson > to cater for fallback attachments: usb.h (the old code) contained a list of > priorities. ugen had the lowest priority and attached if no one else did. An > example was a keyboard with a built-in mouse on one interface. It would be > attached by either mouse or keyboard but not both. An additional driver could > probide both devices. We ended up implementing that differently though: > attachment to interfaces instead of devices. OK. Though I don't see how that is related to the question that I raised. > A probe should not pass any information to the attach phase if it can at all > avoid it. Or at least that is the assumption. If a driver needs info in both > phases, it needs to regenerate it again. The fact that usb_probe is called > again is a kludge, specifically for the description. I am not sure that I understood this part. > I guess that documenting this kludge and updating the comment to state this > fact would be sufficient to solve the problem. I don't see how this follows from what you've written above. -- Andriy Gapon
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