Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751864AbdGRKZh (ORCPT ); Tue, 18 Jul 2017 06:25:37 -0400 Received: from sauhun.de ([88.99.104.3]:36522 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751372AbdGRKYS (ORCPT ); Tue, 18 Jul 2017 06:24:18 -0400 From: Wolfram Sang To: linux-i2c@vger.kernel.org Cc: linux-renesas-soc@vger.kernel.org, linux-media@vger.kernel.org, linux-input@vger.kernel.org, linux-iio@vger.kernel.org, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Wolfram Sang Subject: [PATCH v3 3/4] i2c: sh_mobile: use helper to decide if DMA is useful Date: Tue, 18 Jul 2017 12:23:38 +0200 Message-Id: <20170718102339.28726-4-wsa+renesas@sang-engineering.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170718102339.28726-1-wsa+renesas@sang-engineering.com> References: <20170718102339.28726-1-wsa+renesas@sang-engineering.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1981 Lines: 58 This ensures that we fall back to PIO if the buffer is too small for DMA being useful. Otherwise, we use DMA. A bounce buffer might be applied if the original message buffer is not DMA safe Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-sh_mobile.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c index 2e097d97d258bc..19f45bcd9b35ca 100644 --- a/drivers/i2c/busses/i2c-sh_mobile.c +++ b/drivers/i2c/busses/i2c-sh_mobile.c @@ -145,6 +145,7 @@ struct sh_mobile_i2c_data { struct dma_chan *dma_rx; struct scatterlist sg; enum dma_data_direction dma_direction; + u8 *bounce_buf; }; struct sh_mobile_dt_config { @@ -548,6 +549,8 @@ static void sh_mobile_i2c_dma_callback(void *data) pd->pos = pd->msg->len; pd->stop_after_dma = true; + i2c_release_dma_bounce_buf(pd->msg, pd->bounce_buf); + iic_set_clr(pd, ICIC, 0, ICIC_TDMAE | ICIC_RDMAE); } @@ -595,6 +598,7 @@ static void sh_mobile_i2c_xfer_dma(struct sh_mobile_i2c_data *pd) struct dma_async_tx_descriptor *txdesc; dma_addr_t dma_addr; dma_cookie_t cookie; + u8 *dma_buf = pd->bounce_buf ?: pd->msg->buf; if (PTR_ERR(chan) == -EPROBE_DEFER) { if (read) @@ -608,7 +612,7 @@ static void sh_mobile_i2c_xfer_dma(struct sh_mobile_i2c_data *pd) if (IS_ERR(chan)) return; - dma_addr = dma_map_single(chan->device->dev, pd->msg->buf, pd->msg->len, dir); + dma_addr = dma_map_single(chan->device->dev, dma_buf, pd->msg->len, dir); if (dma_mapping_error(chan->device->dev, dma_addr)) { dev_dbg(pd->dev, "dma map failed, using PIO\n"); return; @@ -665,7 +669,7 @@ static int start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg, pd->pos = -1; pd->sr = 0; - if (pd->msg->len > 8) + if (i2c_check_msg_for_dma(pd->msg, 8, &pd->bounce_buf) == 0) sh_mobile_i2c_xfer_dma(pd); /* Enable all interrupts to begin with */ -- 2.11.0