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[104.188.17.28]) by smtp.gmail.com with ESMTPSA id h70sm14724pgc.36.2019.09.04.13.35.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Sep 2019 13:35:51 -0700 (PDT) Date: Wed, 4 Sep 2019 13:35:48 -0700 From: Bjorn Andersson To: Lee Jones Cc: alokc@codeaurora.org, agross@kernel.org, robh+dt@kernel.org, mark.rutland@arm.com, linux-i2c@vger.kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] i2c: qcom-geni: Provide an option to select FIFO processing Message-ID: <20190904203548.GC580@tuxbook-pro> References: <20190904113613.14997-1-lee.jones@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190904113613.14997-1-lee.jones@linaro.org> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 04 Sep 04:36 PDT 2019, Lee Jones wrote: The subject implies that we select FIFO mode instead of DMA, but that's not really true, because with DMA enabled we still fall back to FIFO for messages below 32 bytes. So what this does it to disable DMA, which neither the subject or the DT property describes. Also missing is a description of why this is needed. Regards, Bjorn > Signed-off-by: Lee Jones > --- > drivers/i2c/busses/i2c-qcom-geni.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c > index a89bfce5388e..dfdbce067827 100644 > --- a/drivers/i2c/busses/i2c-qcom-geni.c > +++ b/drivers/i2c/busses/i2c-qcom-geni.c > @@ -353,13 +353,16 @@ static void geni_i2c_tx_fsm_rst(struct geni_i2c_dev *gi2c) > static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg, > u32 m_param) > { > + struct device_node *np = gi2c->se.dev->of_node; > dma_addr_t rx_dma; > unsigned long time_left; > - void *dma_buf; > + void *dma_buf = NULL; > struct geni_se *se = &gi2c->se; > size_t len = msg->len; > > - dma_buf = i2c_get_dma_safe_msg_buf(msg, 32); > + if (!of_property_read_bool(np, "qcom,geni-se-fifo")) > + dma_buf = i2c_get_dma_safe_msg_buf(msg, 32); > + > if (dma_buf) > geni_se_select_mode(se, GENI_SE_DMA); > else > @@ -392,13 +395,16 @@ static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg, > static int geni_i2c_tx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg, > u32 m_param) > { > + struct device_node *np = gi2c->se.dev->of_node; > dma_addr_t tx_dma; > unsigned long time_left; > - void *dma_buf; > + void *dma_buf = NULL; > struct geni_se *se = &gi2c->se; > size_t len = msg->len; > > - dma_buf = i2c_get_dma_safe_msg_buf(msg, 32); > + if (!of_property_read_bool(np, "qcom,geni-se-fifo")) > + dma_buf = i2c_get_dma_safe_msg_buf(msg, 32); > + > if (dma_buf) > geni_se_select_mode(se, GENI_SE_DMA); > else > -- > 2.17.1 >