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[91.79.175.49]) by smtp.googlemail.com with ESMTPSA id b17-v6sm526992ljj.93.2019.01.30.17.38.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 30 Jan 2019 17:38:02 -0800 (PST) Subject: Re: [PATCH V7 4/5] i2c: tegra: Update transfer timeout 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: <1548864096-20974-1-git-send-email-skomatineni@nvidia.com> <1548864096-20974-4-git-send-email-skomatineni@nvidia.com> From: Dmitry Osipenko Message-ID: <80d5072c-b8b8-c263-bcda-ad008597469e@gmail.com> Date: Thu, 31 Jan 2019 04:38:01 +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: <1548864096-20974-4-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 30.01.2019 19:01, Sowjanya Komatineni пишет: > Tegra194 allows max of 64K bytes and Tegra186 and prior allows > max of 4K bytes of transfer per packet. > > one sec timeout is not enough for transfers more than 10K bytes > at STD bus rate. > > This patch updates I2C transfer timeout based on the transfer size > and I2C bus rate to allow enough time during max transfer size at > lower bus speed. > > Signed-off-by: Sowjanya Komatineni > --- > [V5/V6/V7] : Same as V4 > [V4] : V4 series includes bus clear support and this patch is updated with > fixed timeout of 1sec for bus clear operation. > [V3] : Same as V2 > [V2] : Added this patch in V2 series to allow enough time for data transfer > to happen. > This patch has dependency with DMA patch as TEGRA_I2C_TIMEOUT define > takes argument with this patch. > > drivers/i2c/busses/i2c-tegra.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c > index b30b5da5ce6b..623bf4f275cd 100644 > --- a/drivers/i2c/busses/i2c-tegra.c > +++ b/drivers/i2c/busses/i2c-tegra.c > @@ -25,7 +25,7 @@ > #include > #include > > -#define TEGRA_I2C_TIMEOUT (msecs_to_jiffies(1000)) > +#define TEGRA_I2C_TIMEOUT(ms) (msecs_to_jiffies(ms)) > #define BYTES_PER_FIFO_WORD 4 > > #define I2C_CNFG 0x000 > @@ -901,8 +901,9 @@ static int tegra_i2c_issue_bus_clear(struct tegra_i2c_dev *i2c_dev) > i2c_writel(i2c_dev, reg, I2C_BUS_CLEAR_CNFG); > tegra_i2c_unmask_irq(i2c_dev, I2C_INT_BUS_CLR_DONE); > > - time_left = wait_for_completion_timeout(&i2c_dev->msg_complete, > - TEGRA_I2C_TIMEOUT); > + time_left = wait_for_completion_timeout( > + &i2c_dev->msg_complete, > + TEGRA_I2C_TIMEOUT(1000)); > if (time_left == 0) { > dev_err(i2c_dev->dev, "timed out for bus clear\n"); > return -ETIMEDOUT; > @@ -929,6 +930,7 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev, > u32 *buffer = 0; > int ret = 0; > bool dma = false; > + u16 xfer_time = 100; > > if (msg->flags & I2C_M_RD) > xfer_size = msg->len; > @@ -936,6 +938,9 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev, > xfer_size = msg->len + I2C_PACKET_HEADER_SIZE; > > xfer_size = ALIGN(xfer_size, BYTES_PER_FIFO_WORD); > + xfer_time += DIV_ROUND_CLOSEST((xfer_size * 9) * 1000, > + i2c_dev->bus_clk_rate); Could you please add a clarifying comment for the equation? Shouldn't it be something like this? xfer_time = (P clocks) * DIV_ROUND_UP(xfer_size, (N bytes per P clocks)) / (bus_clk_rate / 1000)