[PATCH RFC 4/7] drm/display: dp-aux-dev: use new DCPD access helpers

[Dmitry Baryshkov]

On Thu, Jan 23, 2025 at 12:05:29PM +0200, Jani Nikula wrote:
> On Fri, 17 Jan 2025, Dmitry Baryshkov <dmitry.baryshkov at linaro.org> wrote:
> > Switch drm_dp_aux_dev.c to use new set of DPCD read / write helpers.
> 
> This might be one of the few places where the old functions and the old
> return value was used in a sensible manner.

Well... Yes and no. What does it mean if we return less bytes? Is that
still a protocol error?

> 
> BR,
> Jani.
> 
> >
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> > ---
> >  drivers/gpu/drm/display/drm_dp_aux_dev.c | 12 +++++-------
> >  1 file changed, 5 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/display/drm_dp_aux_dev.c b/drivers/gpu/drm/display/drm_dp_aux_dev.c
> > index 29555b9f03c8c42681c17c4a01e74a966cf8611f..a31ab3f41efb71fd5f936c24ba5c3b8ebea68a5e 100644
> > --- a/drivers/gpu/drm/display/drm_dp_aux_dev.c
> > +++ b/drivers/gpu/drm/display/drm_dp_aux_dev.c
> > @@ -163,17 +163,16 @@ static ssize_t auxdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
> >  			break;
> >  		}
> >  
> > -		res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
> > -
> > +		res = drm_dp_dpcd_read_data(aux_dev->aux, pos, buf, todo);
> >  		if (res <= 0)
> >  			break;
> >  
> > -		if (copy_to_iter(buf, res, to) != res) {
> > +		if (copy_to_iter(buf, todo, to) != todo) {
> >  			res = -EFAULT;
> >  			break;
> >  		}
> >  
> > -		pos += res;
> > +		pos += todo;
> >  	}
> >  
> >  	if (pos != iocb->ki_pos)
> > @@ -211,12 +210,11 @@ static ssize_t auxdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
> >  			break;
> >  		}
> >  
> > -		res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
> > -
> > +		res = drm_dp_dpcd_write_data(aux_dev->aux, pos, buf, todo);
> >  		if (res <= 0)
> >  			break;
> >  
> > -		pos += res;
> > +		pos += todo;
> >  	}
> >  
> >  	if (pos != iocb->ki_pos)
> 
> -- 
> Jani Nikula, Intel

-- 
With best wishes
Dmitry