From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755199AbbCCBQE (ORCPT ); Mon, 2 Mar 2015 20:16:04 -0500 Received: from mx0a-0016f401.pphosted.com ([67.231.148.174]:10703 "EHLO mx0a-0016f401.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753719AbbCCBQC (ORCPT ); Mon, 2 Mar 2015 20:16:02 -0500 From: Qiao Zhou To: , , , , CC: Qiao Zhou Subject: [PATCH v2] dma: mmp-tdma: refine dma disable and dma-pos update Date: Tue, 3 Mar 2015 09:16:08 +0800 Message-ID: <1425345368-7708-1-git-send-email-zhouqiao@marvell.com> X-Mailer: git-send-email 1.7.0.4 MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.13.68,1.0.33,0.0.0000 definitions=2015-03-02_04:2015-03-02,2015-03-02,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=2 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=7.0.1-1402240000 definitions=main-1503030013 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Below are the refinements. 1. Set DMA abort bit when disabling dma channel. This will clear the remaining data in dma FIFO, to fix channel-swap issue. 2. Read DMA HW pointer when updating DMA status. Previously dma position is calculated by adding one period size in dma interrupt. This is inaccurate/insufficient for some high-quality audio APP. Since interrupt bottom half handler has variable schedule delay, it causes big error when calculating sample delay. Read the actual HW pointer and feedback can improve the accuracy. 3. Do some minor code clean. Signed-off-by: Qiao Zhou --- drivers/dma/mmp_tdma.c | 31 +++++++++++++++++++++++++------ 1 files changed, 25 insertions(+), 6 deletions(-) diff --git a/drivers/dma/mmp_tdma.c b/drivers/dma/mmp_tdma.c index 70c2fa9..b6f4e1f 100644 --- a/drivers/dma/mmp_tdma.c +++ b/drivers/dma/mmp_tdma.c @@ -110,7 +110,7 @@ struct mmp_tdma_chan { struct tasklet_struct tasklet; struct mmp_tdma_desc *desc_arr; - phys_addr_t desc_arr_phys; + dma_addr_t desc_arr_phys; int desc_num; enum dma_transfer_direction dir; dma_addr_t dev_addr; @@ -166,9 +166,12 @@ static void mmp_tdma_enable_chan(struct mmp_tdma_chan *tdmac) static int mmp_tdma_disable_chan(struct dma_chan *chan) { struct mmp_tdma_chan *tdmac = to_mmp_tdma_chan(chan); + u32 tdcr; - writel(readl(tdmac->reg_base + TDCR) & ~TDCR_CHANEN, - tdmac->reg_base + TDCR); + tdcr = readl(tdmac->reg_base + TDCR); + tdcr |= TDCR_ABR; + tdcr &= ~TDCR_CHANEN; + writel(tdcr, tdmac->reg_base + TDCR); tdmac->status = DMA_COMPLETE; @@ -296,12 +299,27 @@ static int mmp_tdma_clear_chan_irq(struct mmp_tdma_chan *tdmac) return -EAGAIN; } +static size_t mmp_tdma_get_pos(struct mmp_tdma_chan *tdmac) +{ + size_t reg; + + if (tdmac->idx == 0) { + reg = __raw_readl(tdmac->reg_base + TDSAR); + reg -= tdmac->desc_arr[0].src_addr; + } else if (tdmac->idx == 1) { + reg = __raw_readl(tdmac->reg_base + TDDAR); + reg -= tdmac->desc_arr[0].dst_addr; + } else + return -EINVAL; + + return reg; +} + static irqreturn_t mmp_tdma_chan_handler(int irq, void *dev_id) { struct mmp_tdma_chan *tdmac = dev_id; if (mmp_tdma_clear_chan_irq(tdmac) == 0) { - tdmac->pos = (tdmac->pos + tdmac->period_len) % tdmac->buf_len; tasklet_schedule(&tdmac->tasklet); return IRQ_HANDLED; } else @@ -343,7 +361,7 @@ static void mmp_tdma_free_descriptor(struct mmp_tdma_chan *tdmac) int size = tdmac->desc_num * sizeof(struct mmp_tdma_desc); gpool = tdmac->pool; - if (tdmac->desc_arr) + if (gpool && tdmac->desc_arr) gen_pool_free(gpool, (unsigned long)tdmac->desc_arr, size); tdmac->desc_arr = NULL; @@ -499,6 +517,7 @@ static enum dma_status mmp_tdma_tx_status(struct dma_chan *chan, { struct mmp_tdma_chan *tdmac = to_mmp_tdma_chan(chan); + tdmac->pos = mmp_tdma_get_pos(tdmac); dma_set_tx_state(txstate, chan->completed_cookie, chan->cookie, tdmac->buf_len - tdmac->pos); @@ -610,7 +629,7 @@ static int mmp_tdma_probe(struct platform_device *pdev) int i, ret; int irq = 0, irq_num = 0; int chan_num = TDMA_CHANNEL_NUM; - struct gen_pool *pool; + struct gen_pool *pool = NULL; of_id = of_match_device(mmp_tdma_dt_ids, &pdev->dev); if (of_id) -- 1.7.0.4