From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753861Ab1HAJlm (ORCPT ); Mon, 1 Aug 2011 05:41:42 -0400 Received: from eu1sys200aog113.obsmtp.com ([207.126.144.135]:52589 "EHLO eu1sys200aog113.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753549Ab1HAJjf (ORCPT ); Mon, 1 Aug 2011 05:39:35 -0400 From: Viresh Kumar To: Cc: , , , , , , , , , , , , , , , Subject: [PATCH V2 13/20] dmaengine/amba-pl08x: max_bytes_per_lli is TRANSFER_SIZE * src_width (not MIN(width)) Date: Mon, 1 Aug 2011 15:07:23 +0530 Message-ID: <816b8264dc71310bd6fca94ed454ebb6e2b2ba5e.1312190881.git.viresh.kumar@st.com> X-Mailer: git-send-email 1.7.2.2 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org max_bytes_per_lli = bd.srcbus.buswidth * PL080_CONTROL_TRANSFER_SIZE_MASK; This is confirmed by ARM support guys. Below is summary of mail exchange with them: [Viresh] What is the total data to be transferred in case source and destination bus widths are different. Suppose, source bus width is 2 bytes and destination is 4 bytes. Now in order to transfer 80 bytes, what should be value of TransferSize field in control reg: 40? or 20?. [David from ARM] The value that is programmed into the TransferSize field should be the number of transfers needed to achieve the required data transfer. So, to transfer 80 bytes, with a Source Width of 2, the TransferSize field = should be programmed with: Total transfer size ------------------- = 40 [Viresh] Will this change if source is 4 bytes and dest is 2? [David] Yes - the calculation then becomes: Total transfer size ------------------- =20 Also, max_bytes_per_lli must be calculated after fixing src and dest widths not before that. So move this code to the correct place. This patch also removes max_bytes_per_lli from earlier print message, as till that point max_bytes_per_lli is unknown. Signed-off-by: Viresh Kumar Acked-by: Linus Walleij --- drivers/dma/amba-pl08x.c | 14 ++++++-------- 1 files changed, 6 insertions(+), 8 deletions(-) diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c index e00a9b5..c29e55c 100644 --- a/drivers/dma/amba-pl08x.c +++ b/drivers/dma/amba-pl08x.c @@ -601,23 +601,17 @@ static int pl08x_fill_llis_for_desc(struct pl08x_driver_data *pl08x, bd.srcbus.buswidth = bd.srcbus.maxwidth; bd.dstbus.buswidth = bd.dstbus.maxwidth; - /* - * Bytes transferred == tsize * MIN(buswidths), not max(buswidths) - */ - max_bytes_per_lli = min(bd.srcbus.buswidth, bd.dstbus.buswidth) * - PL080_CONTROL_TRANSFER_SIZE_MASK; - /* We need to count this down to zero */ bd.remainder = txd->len; pl08x_choose_master_bus(&bd, &mbus, &sbus, cctl); - dev_vdbg(&pl08x->adev->dev, "src=0x%08x%s/%u dst=0x%08x%s/%u len=%zu llimax=%zu\n", + dev_vdbg(&pl08x->adev->dev, "src=0x%08x%s/%u dst=0x%08x%s/%u len=%zu\n", bd.srcbus.addr, cctl & PL080_CONTROL_SRC_INCR ? "+" : "", bd.srcbus.buswidth, bd.dstbus.addr, cctl & PL080_CONTROL_DST_INCR ? "+" : "", bd.dstbus.buswidth, - bd.remainder, max_bytes_per_lli); + bd.remainder); dev_vdbg(&pl08x->adev->dev, "mbus=%s sbus=%s\n", mbus == &bd.srcbus ? "src" : "dst", sbus == &bd.srcbus ? "src" : "dst"); @@ -657,6 +651,10 @@ static int pl08x_fill_llis_for_desc(struct pl08x_driver_data *pl08x, sbus->buswidth = 1; } + /* Bytes transferred = tsize * src width, not MIN(buswidths) */ + max_bytes_per_lli = bd.srcbus.buswidth * + PL080_CONTROL_TRANSFER_SIZE_MASK; + /* * Make largest possible LLIs until less than one bus * width left -- 1.7.2.2