Re: [PATCH] drm/dp_helper: don't return EPROTO for defers (v2)

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 04 Apr 2014, Dave Airlie <airlied@gmail.com> wrote:
> From: Dave Airlie <airlied@redhat.com>
>
> If we get a msg.reply of REPLY_DEFER, we also get an err of 0
> so we fail reads with 0 < size and return -EPROTO instead of trying
> again.
>
> v2: same fix in i2c code.
>
> Found writing MST support.
>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> Signed-off-by: Dave Airlie <airlied@redhat.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index f4babed..2767148 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -386,11 +386,11 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
>  			return err;
>  		}
>  
> -		if (err < size)
> -			return -EPROTO;
>  
>  		switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
>  		case DP_AUX_NATIVE_REPLY_ACK:
> +			if (err < size)
> +				return -EPROTO;
>  			return err;
>  
>  		case DP_AUX_NATIVE_REPLY_NACK:
> @@ -599,8 +599,6 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
>  			return err;
>  		}
>  
> -		if (err < msg->size)
> -			return -EPROTO;
>  
>  		switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) {
>  		case DP_AUX_NATIVE_REPLY_ACK:
> @@ -639,6 +637,8 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
>  			 * Both native ACK and I2C ACK replies received. We
>  			 * can assume the transfer was successful.
>  			 */
> +			if (err < msg->size)
> +				return -EPROTO;
>  			return 0;
>  
>  		case DP_AUX_I2C_REPLY_NACK:
> -- 
> 1.8.5.3
>
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-- 
Jani Nikula, Intel Open Source Technology Center