On Thu, Nov 3, 2016 at 3:17 AM, Jianqun Xu <jay.xu@xxxxxxxxxxxxxx> wrote:
> Reference from drm_dp_aux description (about transfer):
> Upon success, the implementation should return the number of payload bytes
> that were transferred, or a negative error-code on failure. Helpers
> propagate errors from the .transfer() function, with the exception of
> the -EBUSY error, which causes a transaction to be retried. On a short,
> helpers will return -EPROTO to make it simpler to check for failure.
>
> The analogix_dp_transfer will return num_transferred, but if there is none
> byte been transferred, the return value will be 0, which means success, we
> should return error-code if transfer none byte.
>
> for (retry = 0; retry < 32; retry++) {
> err = aux->transfer(aux, &msg);
> if (err < 0) {
> if (err == -EBUSY)
> continue;
>
> goto unlock;
> }
> }
>
> Cc: zain wang <wzz@xxxxxxxxxxxxxx>
> Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
> Signed-off-by: Jianqun Xu <jay.xu@xxxxxxxxxxxxxx>
Reviewed-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
> ---
> 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 cd37ac0..303083a 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;
> + return num_transferred > 0 ? num_transferred : -EBUSY;
> }
> --
> 1.9.1
>
>
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