From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Christ, Austin" Subject: Re: [PATCH 07/12] i2c: qup: use the complete transfer length to choose DMA mode Date: Tue, 27 Feb 2018 15:01:04 -0700 Message-ID: References: <1517644697-30806-1-git-send-email-absahu@codeaurora.org> <1517644697-30806-8-git-send-email-absahu@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1517644697-30806-8-git-send-email-absahu@codeaurora.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Abhishek Sahu , Andy Gross , Wolfram Sang Cc: David Brown , Sricharan R , linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org Tested on Centriq 2400 Reviewed-by: Austin Christ On 2/3/2018 12:58 AM, 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); > > fs_div = ((src_clk_freq / clk_freq) / 2) - 3; > hs_div = 3; > -- Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.