Re: [PATCH] i2c: i2c-omap: Fix BUFSTAT_REG reading

[David Brownell <david-b@pacbell.net>]

On Monday 24 November 2008, ext-eero.nurkkala@nokia.com wrote:
> From: Eero Nurkkala <ext-eero.nurkkala@nokia.com>
> 
> The amount of bytes to receive is read from wrong
> place with omap 2430 and omap 3430.

More simply:  on all OMAPs with highspeed I2C support,
which involves a FIFO and BUFSTAT_REG.


> It is the 6 bits 
> starting from the bit 8 from BUFSTAT_REG that indicate
> this amount. Not the 8 LSB:s. Only 6 LSB:s are used
> for the TX buffer. Moreover, only the 6 LSB:s are
> relevant for XDR.
> 
> Signed-off-by: Eero Nurkkala <ext-eero.nurkkala@nokia.com>
> ---
>  drivers/i2c/busses/i2c-omap.c |   25 +++++++++++++++++++------
>  1 files changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index 96f3bed..630702c 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -672,11 +672,19 @@ omap_i2c_isr(int this_irq, void *dev_id)
>  		if (stat & (OMAP_I2C_STAT_RRDY | OMAP_I2C_STAT_RDR)) {
>  			u8 num_bytes = 1;
>  			if (dev->fifo_size) {

... i.e. if (dev->rev >= OMAP_I2C_REV_ON_2430) ..

> -				if (stat & OMAP_I2C_STAT_RRDY)
> +				if (stat & OMAP_I2C_STAT_RRDY) {
>  					num_bytes = dev->fifo_size;
> -				else
> -					num_bytes = omap_i2c_read_reg(dev,
> +				} else {
> +					if (dev->rev >= OMAP_I2C_REV_ON_2430)
> +						num_bytes =
> +							(omap_i2c_read_reg(dev,
> +							 OMAP_I2C_BUFSTAT_REG)
> +							 >> 8) & 0x3F;
> +					else
> +						num_bytes =
> +							omap_i2c_read_reg(dev,
>  							OMAP_I2C_BUFSTAT_REG);

... so this "else" branch is not needed, neither is the "if" test defining
the two branches ...


> +				}
>  			}
>  			while (num_bytes) {
>  				num_bytes--;
> @@ -711,11 +719,16 @@ omap_i2c_isr(int this_irq, void *dev_id)
>  		if (stat & (OMAP_I2C_STAT_XRDY | OMAP_I2C_STAT_XDR)) {
>  			u8 num_bytes = 1;
>  			if (dev->fifo_size) {

... likewise ...


> -				if (stat & OMAP_I2C_STAT_XRDY)
> +				if (stat & OMAP_I2C_STAT_XRDY) {
>  					num_bytes = dev->fifo_size;
> -				else
> -					num_bytes = omap_i2c_read_reg(dev,
> +				} else {
> +					num_bytes =
> +						omap_i2c_read_reg(dev,
>  							OMAP_I2C_BUFSTAT_REG);
> +
> +					if (dev->rev >= OMAP_I2C_REV_ON_2430)
> +						num_bytes &= 0x3F;

... and likewise.


> +				}
>  			}
>  			while (num_bytes) {
>  				num_bytes--;
> -- 
> 1.6.0
> 
> --
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