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[109.252.192.57]) by smtp.googlemail.com with ESMTPSA id j12sm498818lfc.99.2021.01.12.11.17.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Jan 2021 11:17:08 -0800 (PST) Subject: Re: [PATCH v3] i2c: tegra: Create i2c_writesl_vi() to use with VI I2C for filling TX FIFO To: Sowjanya Komatineni , thierry.reding@gmail.com, jonathanh@nvidia.com, wsa@the-dreams.de Cc: linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org References: <1610478161-4877-1-git-send-email-skomatineni@nvidia.com> <1610478161-4877-2-git-send-email-skomatineni@nvidia.com> From: Dmitry Osipenko Message-ID: <7858911f-4a37-a578-45ed-7522d06d735c@gmail.com> Date: Tue, 12 Jan 2021 22:17:08 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.2 MIME-Version: 1.0 In-Reply-To: <1610478161-4877-2-git-send-email-skomatineni@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org 12.01.2021 22:02, Sowjanya Komatineni пишет: > VI I2C controller has known hardware bug where immediate multiple > writes to TX_FIFO register gets stuck. > > Recommended software work around is to read I2C register after > each write to TX_FIFO register to flush out the data. > > This patch implements this work around for VI I2C controller. You could have kept Thierry's ack since it was given to the fix in general. No need to make v4. > Signed-off-by: Sowjanya Komatineni > --- > drivers/i2c/busses/i2c-tegra.c | 22 +++++++++++++++++++++- > 1 file changed, 21 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c > index 6f08c0c..4a27782 100644 > --- a/drivers/i2c/busses/i2c-tegra.c > +++ b/drivers/i2c/busses/i2c-tegra.c > @@ -326,6 +326,8 @@ static void i2c_writel(struct tegra_i2c_dev *i2c_dev, u32 val, unsigned int reg) > /* read back register to make sure that register writes completed */ > if (reg != I2C_TX_FIFO) > readl_relaxed(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg)); > + else if (i2c_dev->is_vi) > + readl_relaxed(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, I2C_INT_STATUS)); > } > > static u32 i2c_readl(struct tegra_i2c_dev *i2c_dev, unsigned int reg) > @@ -339,6 +341,21 @@ static void i2c_writesl(struct tegra_i2c_dev *i2c_dev, void *data, > writesl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg), data, len); > } > > +static void i2c_writesl_vi(struct tegra_i2c_dev *i2c_dev, void *data, > + unsigned int reg, unsigned int len) > +{ > + u32 *data32 = data; > + > + /* > + * VI I2C controller has known hardware bug where writes get stuck > + * when immediate multiple writes happen to TX_FIFO register. > + * Recommended software work around is to read I2C register after > + * each write to TX_FIFO register to flush out the data. > + */ > + while (len--) > + i2c_writel(i2c_dev, *data32++, reg); > +} > + > static void i2c_readsl(struct tegra_i2c_dev *i2c_dev, void *data, > unsigned int reg, unsigned int len) > { > @@ -811,7 +828,10 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev) > i2c_dev->msg_buf_remaining = buf_remaining; > i2c_dev->msg_buf = buf + words_to_transfer * BYTES_PER_FIFO_WORD; > > - i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer); > + if (i2c_dev->is_vi) > + i2c_writesl_vi(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer); > + else > + i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer); > > buf += words_to_transfer * BYTES_PER_FIFO_WORD; > } > Reviewed-by: Dmitry Osipenko