From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qy0-f21.google.com (mail-qy0-f21.google.com [209.85.221.21]) by ozlabs.org (Postfix) with ESMTP id A1211DDF08 for ; Thu, 18 Dec 2008 07:27:50 +1100 (EST) Received: by qyk14 with SMTP id 14so122348qyk.9 for ; Wed, 17 Dec 2008 12:27:49 -0800 (PST) Message-ID: <4e0b9cb00812171227g47647d31ufaec827ddbab0232@mail.gmail.com> Date: Wed, 17 Dec 2008 21:27:49 +0100 From: "Remi Lefevre" To: "Laurent Pinchart" Subject: Re: FHCI driver adaptation for CPM2 In-Reply-To: <200812171633.58081.laurentp@cse-semaphore.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 References: <4e0b9cb00812170710n3374d558xab3584dc61980756@mail.gmail.com> <200812171633.58081.laurentp@cse-semaphore.com> Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , > Hi Remi, Hi Laurent, > You will find my latest version of the CPM2 FHCI patch attached to this e= - > mail. I've never bothered to clean it as we decided to drop the USB host > function from our device. Thank you very much. Not clean is better than lost. > This depends on the disk. Some will probably not check the SOF token, oth= ers > will do and behave strangely. > >> Also 40% seems quite a lot, even at 1000Hz interruptions, an idea how mu= ch >> does the CRC computation contribute in this CPU hogging ? > > I haven't measured that, but probably not much. The biggest CPU time eate= r > isn't the SOF generation interrupt but the USB packet handling code. The = CPM2 > USB host controller is really too low-level to be usable (except maybe fo= r > specific applications). Comparing the OHCI/UHCI/EHCI and FHCI controllers= is > akin to bit like comparing a full 16550 UART with a software bit-bang > implementation. You can get around with it, it might work for your specif= ic > application, but you shouldn't try a full speed 115200bds communication w= hile > computing a CPU-hungry physical simulation. That's what I was afraid of. I now understand clearly why you didn't expect= that much better performance with CPM3 in a past message (http://ozlabs.org/pipermail/linuxppc-embedded/2008-May/030508.html). Still, as you said, it can have some use for specific applications. Do you remember the throughput you were able to reach with this cpu overhea= d ? > Laurent Pinchart > CSE Semaphore Belgium Kind regards, R=E9mi Lef=E8vre