From patchwork Mon Aug 1 09:37:25 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Viresh KUMAR X-Patchwork-Id: 1025602 Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by demeter2.kernel.org (8.14.4/8.14.4) with ESMTP id p719m7XM032279 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Mon, 1 Aug 2011 09:48:28 GMT Received: from canuck.infradead.org ([2001:4978:20e::1]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1Qnp5k-0006uA-5N; Mon, 01 Aug 2011 09:47:21 +0000 Received: from localhost ([127.0.0.1] helo=canuck.infradead.org) by canuck.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1Qnp5j-0007m4-Ho; Mon, 01 Aug 2011 09:47:19 +0000 Received: from eu1sys200aog114.obsmtp.com ([207.126.144.137]) by canuck.infradead.org with smtps (Exim 4.76 #1 (Red Hat Linux)) id 1Qnoya-0005L2-1s for linux-arm-kernel@lists.infradead.org; Mon, 01 Aug 2011 09:39:58 +0000 Received: from beta.dmz-ap.st.com ([138.198.100.35]) (using TLSv1) by eu1sys200aob114.postini.com ([207.126.147.11]) with SMTP ID DSNKTjZ0XG2eH6WhmvEilkC8Z9SVXJu+CXhL@postini.com; Mon, 01 Aug 2011 09:39:55 UTC Received: from zeta.dmz-ap.st.com (ns6.st.com [138.198.234.13]) by beta.dmz-ap.st.com (STMicroelectronics) with ESMTP id CD7B212D; Mon, 1 Aug 2011 09:39:24 +0000 (GMT) Received: from Webmail-ap.st.com (eapex1hubcas1.st.com [10.80.176.8]) by zeta.dmz-ap.st.com (STMicroelectronics) with ESMTP id B4C0162D; Mon, 1 Aug 2011 09:39:24 +0000 (GMT) Received: from localhost (10.199.88.156) by Webmail-ap.st.com (10.80.176.7) with Microsoft SMTP Server (TLS) id 8.2.234.1; Mon, 1 Aug 2011 17:39:23 +0800 From: Viresh Kumar To: Subject: [PATCH V2 15/20] dmaengine/amba-pl08x: Align lli_len to max(src.width, dst.width) Date: Mon, 1 Aug 2011 15:07:25 +0530 Message-ID: X-Mailer: git-send-email 1.7.2.2 In-Reply-To: References: MIME-Version: 1.0 X-CRM114-Version: 20090807-BlameThorstenAndJenny ( TRE 0.7.6 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20110801_053956_357218_B3D2D52C X-CRM114-Status: GOOD ( 17.38 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.3.1 on canuck.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [207.126.144.137 listed in list.dnswl.org] Cc: pratyush.anand@st.com, rajeev-dlh.kumar@st.com, linux@arm.linux.org.uk, bhupesh.sharma@st.com, shiraz.hashim@st.com, vinod.koul@intel.com, linux-kernel@vger.kernel.org, vipin.kumar@st.com, armando.visconti@st.com, amit.virdi@st.com, vipulkumar.samar@st.com, viresh.linux@gmail.com, deepak.sikri@st.com, dan.j.williams@intel.com, linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter2.kernel.org [140.211.167.43]); Mon, 01 Aug 2011 09:48:28 +0000 (UTC) Currently lli_len is aligned to min of two widths, which looks to be incorrect. Instead it should be aligned to max of both widths. Lets say, total_size = 441 bytes MIN: lets check if min() suits or not: CASE 1: srcwidth = 1, dstwidth = 4 min(src, dst) = 1 i.e. We program transfer size in control reg to 441. Now, till 440 bytes everything is fine, but on the last byte DMAC can't transfer 1 byte to dst, as its width is 4. CASE 2: srcwidth = 4, dstwidth = 1 min(src, dst) = 1 i.e. we program transfer size in control reg to 110 (data transferred = 110 * srcwidth). So, here too 1 byte is left, but on the source side. MAX: Lets check if max() suits or not: CASE 3: srcwidth = 1, dstwidth = 4 max(src, dst) = 4 Aligned size is 440 i.e. We program transfer size in control reg to 440. Now, all 440 bytes will be transferred without any issues. CASE 4: srcwidth = 4, dstwidth = 1 max(src, dst) = 4 Aligned size is 440 i.e. We program transfer size in control reg to 110 (data transferred = 110 * srcwidth). Now, also all 440 bytes will be transferred without any issues. Signed-off-by: Viresh Kumar Acked-by: Linus Walleij --- drivers/dma/amba-pl08x.c | 12 +++++++----- 1 files changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c index 0bdf3b8..ef02fb9 100644 --- a/drivers/dma/amba-pl08x.c +++ b/drivers/dma/amba-pl08x.c @@ -666,20 +666,22 @@ static int pl08x_fill_llis_for_desc(struct pl08x_driver_data *pl08x, * width left */ while (bd.remainder > (mbus->buswidth - 1)) { - size_t lli_len, tsize; + size_t lli_len, tsize, width; /* * If enough left try to send max possible, * otherwise try to send the remainder */ lli_len = min(bd.remainder, max_bytes_per_lli); + /* - * Check against minimum bus alignment: Calculate actual + * Check against maximum bus alignment: Calculate actual * transfer size in relation to bus width and get a - * maximum remainder of the smallest bus width - 1 + * maximum remainder of the highest bus width - 1 */ - tsize = lli_len / min(mbus->buswidth, sbus->buswidth); - lli_len = tsize * min(mbus->buswidth, sbus->buswidth); + width = max(mbus->buswidth, sbus->buswidth); + lli_len = (lli_len / width) * width; + tsize = lli_len / bd.srcbus.buswidth; dev_vdbg(&pl08x->adev->dev, "%s fill lli with single lli chunk of "