Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752503AbcJKOZt (ORCPT ); Tue, 11 Oct 2016 10:25:49 -0400 Received: from mx0b-00176a03.pphosted.com ([67.231.157.48]:54927 "EHLO mx0a-00176a03.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751487AbcJKOZr (ORCPT ); Tue, 11 Oct 2016 10:25:47 -0400 From: Nandor Han To: Vinod Koul , Dan Williams Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Senna Tschudin , Marek Vasut , Nandor Han Subject: [PATCH 1/1] dmaengine: imx-sdma - correct the dma transfer residue calculation Date: Tue, 11 Oct 2016 14:13:41 +0300 Message-Id: <0ee9c1d80055ce97cf6cdcc4aa2ce38b293547b7.1476172445.git.nandor.han@ge.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: References: In-Reply-To: References: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-10-11_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609300000 definitions=main-1610110196 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3124 Lines: 87 The residue calculation was taking in consideration that dma transaction status will be always retrieved in the dma callback used to inform that dma transfer is complete. However this is not the case for all subsystems that use dma. Some subsystems use a timer to check the dma status periodically. Therefore the calculation was updated and residue is calculated accordingly by a) update the residue calculation taking in consideration the last used buffer index by using *buf_ptail* variable and b) chn_real_count (number of bytes transferred) is initialized to zero, when dma channel is created, to avoid using an uninitialized value in residue calculation when dma status is checked without waiting dma complete event. Signed-off-by: Nandor Han --- drivers/dma/imx-sdma.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c index b9629b2..d1651a5 100644 --- a/drivers/dma/imx-sdma.c +++ b/drivers/dma/imx-sdma.c @@ -298,6 +298,7 @@ struct sdma_engine; * @event_id1 for channels that use 2 events * @word_size peripheral access size * @buf_tail ID of the buffer that was processed + * @buf_ptail ID of the previous buffer that was processed * @num_bd max NUM_BD. number of descriptors currently handling */ struct sdma_channel { @@ -309,6 +310,7 @@ struct sdma_channel { unsigned int event_id1; enum dma_slave_buswidth word_size; unsigned int buf_tail; + unsigned int buf_ptail; unsigned int num_bd; unsigned int period_len; struct sdma_buffer_descriptor *bd; @@ -700,6 +702,8 @@ static void sdma_update_channel_loop(struct sdma_channel *sdmac) sdmac->chn_real_count = bd->mode.count; bd->mode.status |= BD_DONE; bd->mode.count = sdmac->period_len; + sdmac->buf_ptail = sdmac->buf_tail; + sdmac->buf_tail = (sdmac->buf_tail + 1) % sdmac->num_bd; /* * The callback is called from the interrupt context in order @@ -710,9 +714,6 @@ static void sdma_update_channel_loop(struct sdma_channel *sdmac) dmaengine_desc_get_callback_invoke(&sdmac->desc, NULL); - sdmac->buf_tail++; - sdmac->buf_tail %= sdmac->num_bd; - if (error) sdmac->status = old_status; } @@ -1186,6 +1187,8 @@ static struct dma_async_tx_descriptor *sdma_prep_slave_sg( sdmac->flags = 0; sdmac->buf_tail = 0; + sdmac->buf_ptail = 0; + sdmac->chn_real_count = 0; dev_dbg(sdma->dev, "setting up %d entries for channel %d.\n", sg_len, channel); @@ -1288,6 +1291,8 @@ static struct dma_async_tx_descriptor *sdma_prep_dma_cyclic( sdmac->status = DMA_IN_PROGRESS; sdmac->buf_tail = 0; + sdmac->buf_ptail = 0; + sdmac->chn_real_count = 0; sdmac->period_len = period_len; sdmac->flags |= IMX_DMA_SG_LOOP; @@ -1385,7 +1390,7 @@ static enum dma_status sdma_tx_status(struct dma_chan *chan, u32 residue; if (sdmac->flags & IMX_DMA_SG_LOOP) - residue = (sdmac->num_bd - sdmac->buf_tail) * + residue = (sdmac->num_bd - sdmac->buf_ptail) * sdmac->period_len - sdmac->chn_real_count; else residue = sdmac->chn_count - sdmac->chn_real_count; -- 2.7.1