Messages in this thread | | | Subject | Re: [PATCH 07/12] i2c: qup: use the complete transfer length to choose DMA mode | From | "Christ, Austin" <> | Date | Tue, 27 Feb 2018 15:01:04 -0700 |
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Tested on Centriq 2400
Reviewed-by: Austin Christ <austinwc@codeaurora.org>
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 <absahu@codeaurora.org> > --- > 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; >
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