[Skiboot] [PATCH v6 02/16] hw/p8-i2c: Speed up SMBUS_WRITE

[Benjamin Herrenschmidt]

On Fri, 2015-05-01 at 15:02 +1000, Gavin Shan wrote:
> For SMBUS_WRITE, the register offset and the following data can be
> sent to I2C bus in one shoot if the FIFO has enough spare space.
> It will help to gain a bit more performance obviously.

Tentative ack. I just want to check it doesn't break writing
to the VPD stuff on palmetto.

Cheers,
Ben.

> Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
> ---
>  hw/p8-i2c.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/p8-i2c.c b/hw/p8-i2c.c
> index 52b9489..1d616fb 100644
> --- a/hw/p8-i2c.c
> +++ b/hw/p8-i2c.c
> @@ -558,10 +558,15 @@ static void p8_i2c_status_data_request(struct p8_i2c_master *master,
>  			rc = p8_i2c_fifo_write(master, master->obuf,
>  					       req->offset_bytes);
>  		}
> +
> +		/* For read, wait address phase to complete */
> +		if (rc || req->op != SMBUS_WRITE)
> +			break;
> +
>  		/* For writes, transition to data phase now */
> -		if (rc == 0 && req->op == SMBUS_WRITE)
> -			master->state = state_data;
> -		break;
> +		master->state = state_data;
> +		fifo_free -= req->offset_bytes;
> +		/* Fall through */
>  	case state_data:
>  		/* Sanity check */
>  		if (master->bytes_sent >= req->rw_len) {