[PATCH] drm/bridge: analogix_dp: Don't return -EBUSY when msg->size is 0 in aux transaction

[wzz@xxxxxxxxxxxxxx (Zain Wang)]

Hi Sean,

     Could you give some comments for this patch?

Thanks
Zain


? 2017/2/13 17:27, zain wang ??:
> The analogix_dp_transfer() will return -EBUSY if num_transferred is zero.
> But sometimes we will send a bare address packet to start the transaction,
> like drm_dp_i2c_xfer() show:
> 	......
> 	/* Send a bare address packet to start the transaction.
> 	 * Zero sized messages specify an address only (bare
> 	 * address) transaction.
> 	 */
> 	msg.buffer = NULL;
> 	msg.size = 0;
> 	err = drm_dp_i2c_do_msg(aux, &msg);
> 	......
>
> In this case, the msg->size is zero, so the num_transferred will be zero too.
> We can't return -EBUSY here, let's we return num_transferred if num_transferred
> equals msg->size.
>
> Signed-off-by: zain wang <wzz at rock-chips.com>
> ---
>   drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> index 303083a..5384aca 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
> @@ -1162,5 +1162,5 @@ ssize_t analogix_dp_transfer(struct analogix_dp_device *dp,
>   		 (msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_NATIVE_READ)
>   		msg->reply = DP_AUX_NATIVE_REPLY_ACK;
>   
> -	return num_transferred > 0 ? num_transferred : -EBUSY;
> +	return (num_transferred == msg->size) ? num_transferred : -EBUSY;
>   }