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[91.79.175.49]) by smtp.googlemail.com with ESMTPSA id 67-v6sm3853477ljc.26.2019.02.06.07.02.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 Feb 2019 07:02:43 -0800 (PST) Subject: Re: [PATCH V13 3/5] i2c: tegra: Add DMA support To: Sowjanya Komatineni , thierry.reding@gmail.com, jonathanh@nvidia.com, mkarthik@nvidia.com, smohammed@nvidia.com, talho@nvidia.com Cc: linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org References: <1549464441-1836-1-git-send-email-skomatineni@nvidia.com> <1549464441-1836-3-git-send-email-skomatineni@nvidia.com> From: Dmitry Osipenko Message-ID: <4ecd3894-a1cb-20dd-8675-26e6e84254e7@gmail.com> Date: Wed, 6 Feb 2019 18:02:42 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <1549464441-1836-3-git-send-email-skomatineni@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 06.02.2019 17:47, Sowjanya Komatineni пишет: > This patch adds DMA support for Tegra I2C. > > Tegra I2C TX and RX FIFO depth is 8 words. PIO mode is used for > transfer size of the max FIFO depth and DMA mode is used for > transfer size higher than max FIFO depth to save CPU overhead. > > PIO mode needs full intervention of CPU to fill or empty FIFO's > and also need to service multiple data requests interrupt for the > same transaction. This adds delay between data bytes of the same > transfer when CPU is fully loaded and some slave devices has > internal timeout for no bus activity and stops transaction to > avoid bus hang. DMA mode is helpful in such cases. > > DMA mode is also helpful for Large transfers during downloading or > uploading FW over I2C to some external devices. > > Signed-off-by: Sowjanya Komatineni > --- [snip] > +static void tegra_i2c_config_fifo_trig(struct tegra_i2c_dev *i2c_dev, > + size_t len) > +{ > + u32 val, reg; > + u8 dma_burst = 0; > + struct dma_slave_config slv_config = {0}; > + struct dma_chan *chan; > + int ret; > + > + if (i2c_dev->hw->has_mst_fifo) > + reg = I2C_MST_FIFO_CONTROL; > + else > + reg = I2C_FIFO_CONTROL; > + val = i2c_readl(i2c_dev, reg); > + > + if (i2c_dev->is_curr_dma_xfer) { > + if (len & 0xF) > + dma_burst = 1; > + else if (len & 0x10) > + dma_burst = 4; > + else > + dma_burst = 8; > + > + if (i2c_dev->msg_read) { > + chan = i2c_dev->rx_dma_chan; > + slv_config.src_addr = i2c_dev->base_phys + > + tegra_i2c_reg_addr(i2c_dev, I2C_RX_FIFO); > + slv_config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES; > + slv_config.src_maxburst = dma_burst; > + > + if (i2c_dev->hw->has_mst_fifo) > + val |= I2C_MST_FIFO_CONTROL_RX_TRIG(dma_burst); > + else > + val |= I2C_FIFO_CONTROL_RX_TRIG(dma_burst); > + } else { > + chan = i2c_dev->tx_dma_chan; > + slv_config.dst_addr = i2c_dev->base_phys + > + tegra_i2c_reg_addr(i2c_dev, I2C_TX_FIFO);; Two ";;" at the end. [snip] Good news: DVC I2C works now and tps6586x probes fine! :) Bad news: atmel-touch still has same problems as in V12 :( DMA-only V13: http://dpaste.com/0XJ1Z8G.txt