12.01.2021 07:06, Sowjanya Komatineni пишет:
> VI I2C don't have DMA support and uses PIO mode all the time.
>
> Current driver uses writesl() to fill TX FIFO based on available
> empty slots and with this seeing strange silent hang during any I2C
> register access after filling TX FIFO with 8 words.
>
> Using writel() followed by i2c_readl() in a loop to write all words
> to TX FIFO instead of using writesl() helps for large transfers in
> PIO mode.
>
> So, this patch creates i2c_writesl_vi() API to use with VI I2C for
> filling TX FIFO.
>
> Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-tegra.c | 20 +++++++++++++++++++-
> 1 file changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index 6f08c0c..e2b7503 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -339,6 +339,21 @@ 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, u32 *data,
> + unsigned int reg, unsigned int len)
> +{
> + /*
> + * Using writesl() to fill VI I2C TX FIFO for transfers more than
> + * 6 words is causing a silent hang on any VI I2C register access
> + * after TX FIFO writes.
> + * So using writel() followed by i2c_readl().
> + */
> + while (len--) {
> + writel(*data++, i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
> + i2c_readl(i2c_dev, I2C_INT_STATUS);
> + }
> +}
> +
> static void i2c_readsl(struct tegra_i2c_dev *i2c_dev, void *data,
> unsigned int reg, unsigned int len)
> {
> @@ -811,7 +826,10 @@ 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, (u32 *)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;
> }
>
Looks almost good, could we please use a relaxed writel and avoid the casting in the code?
Like this:
diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 6f08c0c3238d..4f843b423d83 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
+ 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;
+
+ /*
+ * Using writesl() to fill VI I2C TX FIFO for transfers more than
+ * 6 words is causing a silent hang on any VI I2C register access
+ * after TX FIFO writes. Each write to FIFO should follow by a read
+ * of any I2C register in order to work around the problem.
+ */
+ 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;
}
