On 25/03/13 20:46, Akshay Saraswat wrote:
> From: Gabe Black <gabebl...@google.com>
>
> The exynos s3c24x0 i2c driver wouldn't do the right thing when a NACK was
> received on a read because it didn't attempt a read before waiting for the
> read to finish. Putting a call to ReadWriteByte in the NACK path fixed a
> problem where getting a NACK reading from a device would jam up the bus and
> prevent future accesses like probing from working.
>
> Because other than the ReadWriteByte call the NACK and normal paths were
> almost the same thing, and to avoid future instances of the NACK path not
> working because it's not exercised normally, this change also consolidates
> those two paths.
>
> Signed-off-by: Gabe Black <gabebl...@google.com>
> Signed-off-by: Akshay Saraswat <aksha...@samsung.com>
> ---
> drivers/i2c/s3c24x0_i2c.c | 53
> ++++++++++++++++-------------------------------
> 1 file changed, 18 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/i2c/s3c24x0_i2c.c b/drivers/i2c/s3c24x0_i2c.c
> index d2b4eb0..91298a7 100644
> --- a/drivers/i2c/s3c24x0_i2c.c
> +++ b/drivers/i2c/s3c24x0_i2c.c
> @@ -366,21 +366,25 @@ static int i2c_transfer(struct s3c24x0_i2c *i2c,
> break;
>
> case I2C_READ:
> - if (result == I2C_OK) {
> - writel(I2C_MODE_MR | I2C_TXRX_ENA, &i2c->iicstat);
> - writel(chip, &i2c->iicds);
> - /* send START */
> - writel(readl(&i2c->iicstat) | I2C_START_STOP,
> - &i2c->iicstat);
> - ReadWriteByte(i2c);
> - result = WaitForXfer(i2c);
> + {
> + int was_ok = (result == I2C_OK);
do you really need the was_ok?
If not, please remove it.
> +
> + writel(chip, &i2c->iicds);
> + /* resend START */
> + writel(I2C_MODE_MR | I2C_TXRX_ENA |
> + I2C_START_STOP, &i2c->iicstat);
> + ReadWriteByte(i2c);
> + result = WaitForXfer(i2c);
> +
> + if (was_ok || IsACK(i2c)) {
> i = 0;
> while ((i < data_len) && (result == I2C_OK)) {
> /* disable ACK for final READ */
> - if (i == data_len - 1)
> - writel(readl(&i2c->iiccon)
> - & ~I2CCON_ACKGEN,
> - &i2c->iiccon);
> + if (i == data_len - 1) {
> + writel(readl(&i2c->iiccon) &
> + ~I2CCON_ACKGEN,
> + &i2c->iiccon);
> + }
> ReadWriteByte(i2c);
> result = WaitForXfer(i2c);
> data[i] = readl(&i2c->iicds);
> @@ -388,35 +392,14 @@ static int i2c_transfer(struct s3c24x0_i2c *i2c,
> }
>
> } else {
> - writel(I2C_MODE_MR | I2C_TXRX_ENA, &i2c->iicstat);
> - writel(chip, &i2c->iicds);
> - /* send START */
> - writel(readl(&i2c->iicstat) | I2C_START_STOP,
> - &i2c->iicstat);
> - result = WaitForXfer(i2c);
> -
> - if (IsACK(i2c)) {
> - i = 0;
> - while ((i < data_len) && (result == I2C_OK)) {
> - /* disable ACK for final READ */
> - if (i == data_len - 1)
> - writel(readl(&i2c->iiccon) &
> - ~I2CCON_ACKGEN,
> - &i2c->iiccon);
> - ReadWriteByte(i2c);
> - result = WaitForXfer(i2c);
> - data[i] = readl(&i2c->iicds);
> - i++;
> - }
> - } else {
> - result = I2C_NACK;
> - }
> + result = I2C_NACK;
> }
>
> /* send STOP */
> writel(I2C_MODE_MR | I2C_TXRX_ENA, &i2c->iicstat);
> ReadWriteByte(i2c);
> break;
> + }
>
> default:
> debug("i2c_transfer: bad call\n");
>
Thanks,
Minkyu Kang.
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