From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752224AbeBPEfv (ORCPT ); Thu, 15 Feb 2018 23:35:51 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:47274 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751515AbeBPEfs (ORCPT ); Thu, 15 Feb 2018 23:35:48 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 4306D607E5 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=sricharan@codeaurora.org Subject: Re: [PATCH 07/12] i2c: qup: use the complete transfer length to choose DMA mode To: Abhishek Sahu , Andy Gross , Wolfram Sang Cc: David Brown , linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org References: <1517644697-30806-1-git-send-email-absahu@codeaurora.org> <1517644697-30806-8-git-send-email-absahu@codeaurora.org> From: Sricharan R Message-ID: <4a3d98e2-c340-1a13-eaa4-dde07768e7d8@codeaurora.org> Date: Fri, 16 Feb 2018 10:05:42 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <1517644697-30806-8-git-send-email-absahu@codeaurora.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/3/2018 1:28 PM, Abhishek Sahu wrote: > Currently each message length in complete transfer is being > checked for determining DMA mode and if any of the message length > is less than FIFO length then non DMA mode is being used which > will increase overhead. DMA can be used for any length and it > should be determined with complete transfer length. Now, this > patch introduces DMA threshold length and the transfer will be > done in DMA mode if the total length is greater than this > threshold length. > > Signed-off-by: Abhishek Sahu > --- > drivers/i2c/busses/i2c-qup.c | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c > index 6227a5c..a91fc70 100644 > --- a/drivers/i2c/busses/i2c-qup.c > +++ b/drivers/i2c/busses/i2c-qup.c > @@ -192,6 +192,8 @@ struct qup_i2c_dev { > bool is_dma; > /* To check if the current transfer is using DMA */ > bool use_dma; > + /* The threshold length above which DMA will be used */ > + unsigned int dma_threshold; > struct dma_pool *dpool; > struct qup_i2c_tag start_tag; > struct qup_i2c_bam brx; > @@ -1294,7 +1296,8 @@ static int qup_i2c_xfer_v2(struct i2c_adapter *adap, > int num) > { > struct qup_i2c_dev *qup = i2c_get_adapdata(adap); > - int ret, len, idx = 0; > + int ret, idx = 0; > + unsigned int total_len = 0; > > qup->bus_err = 0; > qup->qup_err = 0; > @@ -1320,14 +1323,13 @@ static int qup_i2c_xfer_v2(struct i2c_adapter *adap, > goto out; > } > > - len = (msgs[idx].len > qup->out_fifo_sz) || > - (msgs[idx].len > qup->in_fifo_sz); > - > - if (is_vmalloc_addr(msgs[idx].buf) || !len) > + if (is_vmalloc_addr(msgs[idx].buf)) > break; > + > + total_len += msgs[idx].len; > } > > - if (idx == num) > + if (idx == num && total_len > qup->dma_threshold) > qup->use_dma = true; > } > > @@ -1587,6 +1589,7 @@ static int qup_i2c_probe(struct platform_device *pdev) > > size = QUP_INPUT_FIFO_SIZE(io_mode); > qup->in_fifo_sz = qup->in_blk_sz * (2 << size); > + qup->dma_threshold = min(qup->out_fifo_sz, qup->in_fifo_sz); The patch is fine. small nit, you can avoid this global dma_threshold. Instead have it locally in qup_i2c_xfer_v2 itself. Regards, Sricharan -- "QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation