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[91.79.175.49]) by smtp.googlemail.com with ESMTPSA id c12sm4243073lfh.48.2019.02.07.06.52.16 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Feb 2019 06:52:17 -0800 (PST) Subject: Re: [PATCH V14 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: <1549480569-24860-1-git-send-email-skomatineni@nvidia.com> <1549480569-24860-3-git-send-email-skomatineni@nvidia.com> From: Dmitry Osipenko Message-ID: Date: Thu, 7 Feb 2019 17:52:16 +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: <1549480569-24860-3-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 22:16, 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] > @@ -1124,6 +1453,10 @@ static int tegra_i2c_probe(struct platform_device *pdev) > } > } > > + ret = tegra_i2c_init_dma(i2c_dev); > + if (ret < 0) > + goto disable_div_clk; > + > ret = tegra_i2c_init(i2c_dev); > if (ret) { > dev_err(&pdev->dev, "Failed to initialize i2c controller\n"); Missing DMA resourcing release on probe failure. diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c index 7921d3e6237d..11f25357b843 100644 --- a/drivers/i2c/busses/i2c-tegra.c +++ b/drivers/i2c/busses/i2c-tegra.c @@ -1612,14 +1612,14 @@ static int tegra_i2c_probe(struct platform_device *pdev) ret = tegra_i2c_init(i2c_dev, false); if (ret) { dev_err(&pdev->dev, "Failed to initialize i2c controller\n"); - goto disable_div_clk; + goto release_dma; } ret = devm_request_irq(&pdev->dev, i2c_dev->irq, tegra_i2c_isr, 0, dev_name(&pdev->dev), i2c_dev); if (ret) { dev_err(&pdev->dev, "Failed to request irq %i\n", i2c_dev->irq); - goto disable_div_clk; + goto release_dma; } i2c_set_adapdata(&i2c_dev->adapter, i2c_dev); @@ -1633,10 +1633,13 @@ static int tegra_i2c_probe(struct platform_device *pdev) ret = i2c_add_numbered_adapter(&i2c_dev->adapter); if (ret) - goto disable_div_clk; + goto release_dma; return 0; +release_dma: + tegra_i2c_release_dma(i2c_dev); + disable_div_clk: if (i2c_dev->is_multimaster_mode) clk_disable(i2c_dev->div_clk);