From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-x22d.google.com (mail-pf0-x22d.google.com [IPv6:2607:f8b0:400e:c00::22d]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 15DE381E10 for ; Tue, 17 Jan 2017 22:41:21 -0800 (PST) Received: by mail-pf0-x22d.google.com with SMTP id y143so1912102pfb.0 for ; Tue, 17 Jan 2017 22:41:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:references:cc:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding; bh=OS9A3GhFx8XLWdkIM8HVGMyVc8UfLaom8Uza749uexA=; b=iiNZilL4U8SRC/+IpnBmCLoSlsYoSuDiviS0AUPMYh5xSzCBWArTA1ZWMCdDMnpvyF WByxgpFcoalW8cBzlkihueqkeagfwTFHEUcub8Yi3h5yjkbcFpFJJbjWbeQniSH/i5lD fPXM5nFmwikLug37ODkncevUaTKfvJAS6ztdY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:cc:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=OS9A3GhFx8XLWdkIM8HVGMyVc8UfLaom8Uza749uexA=; b=hU3yQB/0m9XlGzctKH62lcQMzN6GRZJ9l2nQ1PGg/lHswGXIES0pyNYAr6455N1d4S NtlO/xDTKCTWU3aCva1SdQw1zSNqs8G2wQqJCqmrBppt7b7Dw015BpPuEWjgLSkOVUyd 5CynG8U6CLaFYcs3Endo9KaFIY32tdQDRGv/PreirFJiWktEqGmEih2OWbJ39MVLOda+ Q3Bw6GQlTl3rHjMQIjzAM8385O0AN4uKbUbKVr8vo171YgVG2FbUzcnUnOdjrJsCjd+m XV9E6OTQTpu5x/qocuDN8S7Z32vH34fxNZgymCAui4OMqTcTf+v0iiAl5NYYwj0hgk42 JloQ== X-Gm-Message-State: AIkVDXJhGe3HRncGwIlTNsC6yBRJWXdxpmrlVvDG0xc+LzcfpKGPCuzgdQVWb2qlajVqTmtk X-Received: by 10.98.141.194 with SMTP id p63mr1963574pfk.185.1484721681231; Tue, 17 Jan 2017 22:41:21 -0800 (PST) Received: from [10.229.36.249] ([119.145.15.121]) by smtp.gmail.com with ESMTPSA id j128sm60385314pfg.73.2017.01.17.22.41.19 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 17 Jan 2017 22:41:20 -0800 (PST) To: "Tian, Feng" , "edk2-devel@lists.01.org" References: <47a8c44f-e72f-a993-a0a0-0ee38d2735d3@linaro.org> <7F1BAD85ADEA444D97065A60D2E97EE566E3700D@SHSMSX101.ccr.corp.intel.com> Cc: "Zeng, Star" From: Heyi Guo Message-ID: <76e11520-b4ba-7c78-cd55-d3d5502a4967@linaro.org> Date: Wed, 18 Jan 2017 14:41:17 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <7F1BAD85ADEA444D97065A60D2E97EE566E3700D@SHSMSX101.ccr.corp.intel.com> Subject: Re: Why is USB_BOOT_IO_BLOCKS set to 128? X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 18 Jan 2017 06:41:21 -0000 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi Feng, Digging in the code history, I found the original value of USB_BOOT_IO_BLOCKS was 64, but it was changed to be 128 by the commit 41e8ff2. So could you help to explain my questions as below? 1. What was the exact reason to change this value? 2. And for the comment in the code, it says "Max carried size is 512B * 128 = 64KB", but we see that some USB CDROM has block size of 2KB. So do we mean something for 64KB max size? 3. From USB specification perspective, is there any limit for transfer length, or the device should be able to transfer arbitrary length? commit 41e8ff2781f3ca14f73ef5f39e781ccba8cb373d Author: yshang1 Date: Mon Oct 8 06:14:13 2007 +0000 Fixed unexpected timeout in Usb MassStorage Driver. Fixed unexpected timeout in Uhci/Ehci driver. git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@4038 6f19259b-4bc3-4df7-8a09-765794883524 Thanks and regards, Heyi 在 10/19/2016 10:10 AM, Tian, Feng 写道: > It's just an experience value and has been here about 10 years... > > Which usb brand/model name do you have problem on? > > Thanks > Feng > > -----Original Message----- > From: Heyi Guo [mailto:heyi.guo@linaro.org] > Sent: Wednesday, October 19, 2016 9:57 AM > To: edk2-devel@lists.01.org > Cc: Tian, Feng ; Zeng, Star > Subject: [edk2] Why is USB_BOOT_IO_BLOCKS set to 128? > > Dear experts, > > Could anyone help to explain why USB_BOOT_IO_BLOCKS in MdeModulePkg/Bus/Usb/UsbMassStorageDxe/UsbMassBoot.h is set to 128? > > We found on some platforms this value may cause USB boot failure and > *64* blocks will make them work. Though we have not got the final root cause, it will be really helpful if you can tell the reason of setting it to 128 and possible root cause for such issue. > > Thanks and regards, > > Heyi >