From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Date: Sat, 8 Feb 2014 15:01:11 +0100 Subject: [U-Boot] [PATCH V2] ush: ehci: initialize altnext pointers in QH In-Reply-To: <1391792030-8457-1-git-send-email-swarren@wwwdotorg.org> References: <1391792030-8457-1-git-send-email-swarren@wwwdotorg.org> Message-ID: <201402081501.11120.marex@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Friday, February 07, 2014 at 05:53:50 PM, Stephen Warren wrote: > From: Stephen Warren > > Section 4.10.2 "Advance Queue" of ehci-specification-for-usb.pdf > specifies how an EHCI controller loads a new QTD for processing if the > QH is not already marked as active. It states: > > ===== > If the field Bytes to Transfer is not zero and the T-bit in the Alternate > Next qTD Pointer is set to zero, then the host controller uses the > Alternate Next qTD Pointer. Otherwise, the host controller uses the Next > qTD Pointer. If Next qTD Pointer?s T-bit is set to a one, then the host > controller exits this state and uses the horizontal pointer to the next > schedule data structure. > ===== > > Hence, we must ensure that the alternate next QTD pointer's T-bit > (TERMINATE) is set, so the EHCI controller knows to use the next QTD > pointer. > > Signed-off-by: Stephen Warren Applied, thanks. Best regards, Marek Vasut