From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 22 May 2002 00:33:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 22 May 2002 00:33:53 -0400 Received: from mta5.snfc21.pbi.net ([206.13.28.241]:22433 "EHLO mta5.snfc21.pbi.net") by vger.kernel.org with ESMTP id ; Wed, 22 May 2002 00:33:52 -0400 Date: Tue, 21 May 2002 21:33:03 -0700 From: David Brownell Subject: Re: [linux-usb-devel] Re: What to do with all of the USB UHCI drivers in the kernel ? To: "Maksim (Max) Krasnyanskiy" Cc: linux-kernel@vger.kernel.org, linux-usb-devel@lists.sourceforge.net Message-id: <3CEB1F7F.4000000@pacbell.net> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii; format=flowed Content-transfer-encoding: 7BIT X-Accept-Language: en-us, en, fr User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.9) Gecko/20020408 In-Reply-To: <5.1.0.14.2.20020521133408.068d2ef8@mail1.qualcomm.com> <5.1.0.14.2.20020521122422.06b21188@mail1.qualcomm.com> <5.1.0.14.2.20020521122422.06b21188@mail1.qualcomm.com> <20020521195925.GA2623@kroah.com> <5.1.0.14.2.20020521133408.068d2ef8@mail1.qualcomm.com> <5.1.0.14.2.20020521164157.06b68430@mail1.qualcomm.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Maksim (Max) Krasnyanskiy wrote: > > One-shot interrupt transfers are broken in *-hcd drivers. core/hcd.c > returns EINVAL if urb->interval==0. Hmm, eventually that automagic resubmit model needs to go away, in favor of a straight queued transfer model -- where in effect there are _only_ "one shot" transfers, which for interrupts are just going to hang out on endpoint queues that are properly scheduled. That's needed to make interrupt reads and writes have the same transfer model ... right now interrupt OUT transfers don't work very well. (And they'll be the most common type when we eventually get those device/target side driver APIs sorted.) Meanwhile, I suppose I can see wanting access to that UHCI-ism. However your patch would do that wrong, since it should only apply to interrupt transfers. > usb-uhci-hcd has to be fixed. > btw It tries to round interval value even thought it's done by hcd.c That was one of my quick-review comments too. It doesn't hurt, it's just one of several URB sanity-check/preprocessing steps that doesn't need to be in every driver. > On a side note. Why are URBs still not SLABified ? Hasn't seemed to be necessary. kmalloc() is slabified already, so it's not clear that a control/bulk/interrupt URB pool shared between drivers -- size, maybe a handful -- would be better than sharing that same memory with other kernel code. - Dave