Re: [PATCH] drm/bridge: analogix_dp: return error if transfer none byte

[Archit Taneja]

On 11/15/2016 10:39 PM, Sean Paul wrote:
> 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>

queued to drm-misc.

> > ---
> >  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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