From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Ball Subject: Re: [PATCH 3/3] dw_mmc: Handle unaligned data submission correctly Date: Fri, 22 Mar 2013 12:52:12 -0400 Message-ID: <87vc8jml6r.fsf@octavius.laptop.org> References: <1363085593-22214-1-git-send-email-markos.chandras@imgtec.com> <1363085593-22214-3-git-send-email-markos.chandras@imgtec.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from void.printf.net ([89.145.121.20]:38460 "EHLO void.printf.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1160998Ab3CVQwP (ORCPT ); Fri, 22 Mar 2013 12:52:15 -0400 In-Reply-To: <1363085593-22214-3-git-send-email-markos.chandras@imgtec.com> (Markos Chandras's message of "Tue, 12 Mar 2013 10:53:13 +0000") Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Markos Chandras Cc: linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, Seungwon Jeon , Jaehoon Chung Hi, On Tue, Mar 12 2013, Markos Chandras wrote: > Commit f9c2a0dc42a6938ff2a80e55ca2bbd1d5581c72e > "mmc: dw_mmc: Fix PIO mode with support of highmem" introduced > a regression since v3.2 making the mmc_test hang on test #13 > with a "Data starvation by host timeout" interrupt. > > This is because, sg_mapping_iter is used to iterate through the > data which spans on multiple pages. The problem is detected on > unaligned data submission where the code previously checked for > !(sg_next(host->sg)) which is true because we only have a single > scatter/gather list which then expands to multiple pages. > Therefore, the driver incorrectly assumed that this was the last > list item and submitted unaligned data to the mmc device. This > overflowed the FIFO on the device before all the data were written > to it. The code was fixed to only submit unaligned data when we are > handling the last sg_miter item by checking whether we reached > the desired data length or not. > > The patch was tested against mmc_test and all the tests passed. > > Signed-off-by: Markos Chandras > Cc: Seungwon Jeon > Cc: Jaehoon Chung > Cc: Chris Ball Thanks, pushed to mmc-next for 3.10. - Chris. -- Chris Ball One Laptop Per Child