[linux-sunxi] Re: [PATCH v3 04/11] drm/sun4i: abstract the layer type

Maxime Ripard
2017-04-05T08:09:58Z

On Wed, Apr 05, 2017 at 01:23:15PM +0800, Icenowy Zheng wrote:
>
> 2017?4?5? 10:27? Chen-Yu Tsai <wens@csie.org>???
> >
> > On Wed, Apr 5, 2017 at 3:53 AM, Icenowy Zheng <icenowy@aosc.io> wrote:
> > >
> > >
> > > ? 2017?04?05? 03:28, Sean Paul ??:
> > >>
> > >> On Thu, Mar 30, 2017 at 03:46:06AM +0800, Icenowy Zheng wrote:
> > >>>
> > >>> As we are going to add support for the Allwinner DE2 Mixer in sun4i-drm
> > >>> driver, we will finally have two types of layer.
> > >>>
> > >>> Abstract the layer type to void * and a ops struct, which contains the
> > >>> only function used by crtc -- get the drm_plane struct of the layer.
> > >>>
> > >>> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
> > >>> ---
> > >>> Refactored patch in v3.
> > >>>
> > >>>? drivers/gpu/drm/sun4i/sun4i_crtc.c? | 19 +++++++++++--------
> > >>>? drivers/gpu/drm/sun4i/sun4i_crtc.h? |? 3 ++-
> > >>>? drivers/gpu/drm/sun4i/sun4i_layer.c | 19 ++++++++++++++++++-
> > >>>? drivers/gpu/drm/sun4i/sun4i_layer.h |? 2 +-
> > >>>? drivers/gpu/drm/sun4i/sunxi_layer.h | 17 +++++++++++++++++
> > >>>? 5 files changed, 49 insertions(+), 11 deletions(-)
> > >>>? create mode 100644 drivers/gpu/drm/sun4i/sunxi_layer.h
> > >>>
> > >>> diff --git a/drivers/gpu/drm/sun4i/sun4i_crtc.c
> > >>> b/drivers/gpu/drm/sun4i/sun4i_crtc.c
> > >>> index 3c876c3a356a..33854ee7f636 100644
> > >>> --- a/drivers/gpu/drm/sun4i/sun4i_crtc.c
> > >>> +++ b/drivers/gpu/drm/sun4i/sun4i_crtc.c
> > >>> @@ -29,6 +29,7 @@
> > >>>? #include "sun4i_crtc.h"
> > >>>? #include "sun4i_drv.h"
> > >>>? #include "sun4i_layer.h"
> > >>> +#include "sunxi_layer.h"
> > >>>? #include "sun4i_tcon.h"
> > >>>
> > >>>? static void sun4i_crtc_atomic_begin(struct drm_crtc *crtc,
> > >>> @@ -149,7 +150,7 @@ struct sun4i_crtc *sun4i_crtc_init(struct drm_device
> > >>> *drm,
> > >>>???????? scrtc->tcon = tcon;
> > >>>
> > >>>???????? /* Create our layers */
> > >>> -?????? scrtc->layers = sun4i_layers_init(drm, scrtc->backend);
> > >>> +?????? scrtc->layers = (void **)sun4i_layers_init(drm, scrtc);
> > >>>???????? if (IS_ERR(scrtc->layers)) {
> > >>>???????????????? dev_err(drm->dev, "Couldn't create the planes\n");
> > >>>???????????????? return NULL;
> > >>> @@ -157,14 +158,15 @@ struct sun4i_crtc *sun4i_crtc_init(struct
> > >>> drm_device *drm,
> > >>>
> > >>>???????? /* find primary and cursor planes for drm_crtc_init_with_planes
> > >>> */
> > >>>???????? for (i = 0; scrtc->layers[i]; i++) {
> > >>> -?????????????? struct sun4i_layer *layer = scrtc->layers[i];
> > >>> +?????????????? void *layer = scrtc->layers[i];
> > >>> +?????????????? struct drm_plane *plane =
> > >>> scrtc->layer_ops->get_plane(layer);
> > >>>
> > >>> -?????????????? switch (layer->plane.type) {
> > >>> +?????????????? switch (plane->type) {
> > >>>???????????????? case DRM_PLANE_TYPE_PRIMARY:
> > >>> -?????????????????????? primary = &layer->plane;
> > >>> +?????????????????????? primary = plane;
> > >>>???????????????????????? break;
> > >>>???????????????? case DRM_PLANE_TYPE_CURSOR:
> > >>> -?????????????????????? cursor = &layer->plane;
> > >>> +?????????????????????? cursor = plane;
> > >>>???????????????????????? break;
> > >>>???????????????? default:
> > >>>???????????????????????? break;
> > >>> @@ -190,10 +192,11 @@ struct sun4i_crtc *sun4i_crtc_init(struct
> > >>> drm_device *drm,
> > >>>???????? /* Set possible_crtcs to this crtc for overlay planes */
> > >>>???????? for (i = 0; scrtc->layers[i]; i++) {
> > >>>???????????????? uint32_t possible_crtcs =
> > >>> BIT(drm_crtc_index(&scrtc->crtc));
> > >>> -?????????????? struct sun4i_layer *layer = scrtc->layers[i];
> > >>> +?????????????? void *layer = scrtc->layers[i];
> > >>> +?????????????? struct drm_plane *plane =
> > >>> scrtc->layer_ops->get_plane(layer);
> > >>>
> > >>> -?????????????? if (layer->plane.type == DRM_PLANE_TYPE_OVERLAY)
> > >>> -?????????????????????? layer->plane.possible_crtcs = possible_crtcs;
> > >>> +?????????????? if (plane->type == DRM_PLANE_TYPE_OVERLAY)
> > >>> +?????????????????????? plane->possible_crtcs = possible_crtcs;
> > >>>???????? }
> > >>>
> > >>>???????? return scrtc;
> > >>> diff --git a/drivers/gpu/drm/sun4i/sun4i_crtc.h
> > >>> b/drivers/gpu/drm/sun4i/sun4i_crtc.h
> > >>> index 230cb8f0d601..a4036ee44cf8 100644
> > >>> --- a/drivers/gpu/drm/sun4i/sun4i_crtc.h
> > >>> +++ b/drivers/gpu/drm/sun4i/sun4i_crtc.h
> > >>> @@ -19,7 +19,8 @@ struct sun4i_crtc {
> > >>>
> > >>>???????? struct sun4i_backend??????????? *backend;
> > >>>???????? struct sun4i_tcon?????????????? *tcon;
> > >>> -?????? struct sun4i_layer????????????? **layers;
> > >>> +?????? void??????????????????????????? **layers;
> > >>> +?????? const struct sunxi_layer_ops??? *layer_ops;
> > >>
> > >>
> > >> I think you should probably take a different approach to abstract the
> > >> layer
> > >> type. How about creating
> > >>
> > >> struct sunxi_layer {
> > >>???????? struct drm_plane plane;
> > >> }
> > >>
> > >> base and then subclassing that for sun4i and sun8i? By doing this you can
> > >> avoid
> > >> the nasty casting and you can also get rid of the get_plane() hook and
> > >> layer_ops.
> > >
> > >
> > > For the situation that using ** things are easily to get weird.
> >
> > That code could be reworked, by initializing the layers directly within
> > the crtc init code. If you look at rockchip's drm driver, you'll see
> > they do this. There is a good reason to do it this way, as you need
> > to first create the primary and cursor layers, pass them in when you
> > create the crtc, then initialize any additional layers with the
> > possible_crtcs bitmap.
>
> But furthurly maybe more layers will be created for DE2 mixer, and
> may even depends on mixer type (On A83T/H3/A64/H5 mixer1 has fewer
> channel than mixer0).

You'll always have one primary and one cursor plane, no matter how
much planes you support.

Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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