From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Date: Fri, 03 May 2013 08:46:01 -0600 Subject: [U-Boot] [PATCH 2/3] ARM: Tegra: USB: Add driver support for Tegra30/Tegra114 In-Reply-To: <1367578411.1302.6.camel@jilin-desktop> References: <1367227275-7713-1-git-send-email-jilin@nvidia.com> <1367227275-7713-3-git-send-email-jilin@nvidia.com> <5182BEAF.5090004@wwwdotorg.org> <1367578411.1302.6.camel@jilin-desktop> Message-ID: <5183CDA9.8040100@wwwdotorg.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 05/03/2013 04:53 AM, Jim Lin wrote: > On Fri, 2013-05-03 at 03:29 +0800, Stephen Warren wrote: >> On 04/29/2013 03:21 AM, Jim Lin wrote: >>> Tegra30 and Tegra114 are compatible except >>> 1. T30 takes 55 ms to finish Port Reset. T114 takes >>> 50 ms. >> >> Is that 55-vs-50 some aspect of the HW specification itself, or the >> overall result of multiple separate delays? I ask because the statement >> that one piece of HW differs from another only in a delay, especially >> where that delay is enormous in HW terms, seem very unusual. > > 50 ms comes from USB 2.0 specification for root port. > 55 ms comes from T30 Technical Reference Manual. OK, I see this value is indeed in the TRM, so I guess the code is OK. > Overall result of multiple separate delays. That doesn't seem true though; the TRM simply documents a single 55ms delay, not a set of delays that add up to 55ms.