[U-Boot] [PATCH] I2C: S3C24X0: Bug fixes in i2c_transfer

This patch corrects the following issues
1) Write the correct M/T Stop value to I2CSTAT after i2c write. According to the spec, after finish the data transmission, we should write a M/T Stop (I2C_MODE_MT | I2C_TXRX_ENA) to I2CSTAT instead of a M/R Stop (I2C_MODE_MR | I2C_TXRX_ENA). 2) Not split the write to I2CSTAT into 2 steps in i2c read. According to the spec, we should write the combined M/R Start value to I2CSTAT after setting the slave address to I2CDS 3) Fix the mistake of making an equality check to an assignment. In the case of I2C write with the zero-length address, while tranfering the data, it should be an equality check (==) instead of an assignment (=).
Signed-off-by: Tom Wai-Hong Tam waihong@chromium.org Signed-off-by: Rajeshwari Shinde rajeshwari.s@samsung.com --- drivers/i2c/s3c24x0_i2c.c | 14 ++++++-------- 1 files changed, 6 insertions(+), 8 deletions(-)
diff --git a/drivers/i2c/s3c24x0_i2c.c b/drivers/i2c/s3c24x0_i2c.c index 00308b5..46d2506 100644 --- a/drivers/i2c/s3c24x0_i2c.c +++ b/drivers/i2c/s3c24x0_i2c.c @@ -324,7 +324,7 @@ static int i2c_transfer(struct s3c24x0_i2c *i2c, writel(I2C_MODE_MT | I2C_TXRX_ENA | I2C_START_STOP, &i2c->iicstat); i = 0; - while ((i < data_len) && (result = I2C_OK)) { + while ((i < data_len) && (result == I2C_OK)) { result = WaitForXfer(i2c); writel(data[i], &i2c->iicds); ReadWriteByte(i2c); @@ -336,17 +336,16 @@ static int i2c_transfer(struct s3c24x0_i2c *i2c, result = WaitForXfer(i2c);
/* send STOP */ - writel(I2C_MODE_MR | I2C_TXRX_ENA, &i2c->iicstat); + writel(I2C_MODE_MT | I2C_TXRX_ENA, &i2c->iicstat); ReadWriteByte(i2c); break;
case I2C_READ: if (addr && addr_len) { - writel(I2C_MODE_MT | I2C_TXRX_ENA, &i2c->iicstat); writel(chip, &i2c->iicds); /* send START */ - writel(readl(&i2c->iicstat) | I2C_START_STOP, - &i2c->iicstat); + writel(I2C_MODE_MT | I2C_TXRX_ENA | I2C_START_STOP, + &i2c->iicstat); result = WaitForXfer(i2c); if (IsACK(i2c)) { i = 0; @@ -380,11 +379,10 @@ 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); + writel(I2C_MODE_MR | I2C_TXRX_ENA | I2C_START_STOP, + &i2c->iicstat); result = WaitForXfer(i2c);
if (IsACK(i2c)) {

On Tue, Feb 19, 2013 at 8:19 PM, Rajeshwari Shinde <rajeshwari.s@samsung.com
wrote:
This patch corrects the following issues
- Write the correct M/T Stop value to I2CSTAT after i2c write. According to the spec, after finish the data transmission, we should write a M/T Stop (I2C_MODE_MT | I2C_TXRX_ENA) to I2CSTAT instead of a M/R Stop (I2C_MODE_MR | I2C_TXRX_ENA).
- Not split the write to I2CSTAT into 2 steps in i2c read. According to the spec, we should write the combined M/R Start value to I2CSTAT after setting the slave address to I2CDS
- Fix the mistake of making an equality check to an assignment. In the case of I2C write with the zero-length address, while tranfering
the data, it should be an equality check (==) instead of an assignment (=).
Signed-off-by: Tom Wai-Hong Tam waihong@chromium.org Signed-off-by: Rajeshwari Shinde rajeshwari.s@samsung.com
Tested-by: Hung-ying Tyan tyanh@chromium.org

Hi Heiko,
Do let me know if you have any comments on this patch. Would you consider it for I2C branch or should it go through u-boot-samsung?
Regards, Rajeshwari
On Wed, Mar 6, 2013 at 2:57 PM, Hung-ying Tyan tyanh@chromium.org wrote:
On Tue, Feb 19, 2013 at 8:19 PM, Rajeshwari Shinde <rajeshwari.s@samsung.com
wrote:
This patch corrects the following issues
- Write the correct M/T Stop value to I2CSTAT after i2c write. According to the spec, after finish the data transmission, we should write a M/T Stop (I2C_MODE_MT | I2C_TXRX_ENA) to I2CSTAT instead of a M/R Stop (I2C_MODE_MR | I2C_TXRX_ENA).
- Not split the write to I2CSTAT into 2 steps in i2c read. According to the spec, we should write the combined M/R Start value to I2CSTAT after setting the slave address to I2CDS
- Fix the mistake of making an equality check to an assignment. In the case of I2C write with the zero-length address, while tranfering
the data, it should be an equality check (==) instead of an assignment (=).
Signed-off-by: Tom Wai-Hong Tam waihong@chromium.org Signed-off-by: Rajeshwari Shinde rajeshwari.s@samsung.com
Tested-by: Hung-ying Tyan tyanh@chromium.org
U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
participants (3)
-
Hung-ying Tyan
-
Rajeshwari Birje
-
Rajeshwari Shinde