Re: [PATCH v9 00/23] drm/rockchip: RK356x VOP2 support

Sascha Hauer
2022-04-05T09:39:19Z

On Sat, Apr 02, 2022 at 09:37:17AM +0800, Andy Yan wrote:
> Hi Sacha:
>
> On 4/1/22 20:52, Sascha Hauer wrote:
> > --
> > >From cbc03073623a7180243331ac24c3afaf9dec7522 Mon Sep 17 00:00:00 2001
> > From: Sascha Hauer<s.hauer@pengutronix.de>
> > Date: Fri, 1 Apr 2022 14:48:49 +0200
> > Subject: [PATCH] fixup! drm: rockchip: Add VOP2 driver
> >
> > ---
> > drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 14 ++++++++++++++
> > 1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> > index 7dba7b9b63dc6..1421bf2f133f1 100644
> > --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> > @@ -2287,6 +2287,20 @@ static int vop2_create_crtc(struct vop2 *vop2)
> > }
> > }
> > + if (vop2->data->soc_id == 3566) {
> > + /*
> > + * On RK3566 these windows don't have an independent
> > + * framebuffer. They share the framebuffer with smart0,
> > + * esmart0 and cluster0 respectively.
> > + */
> > + switch (win->data->phys_id) {
> > + case ROCKCHIP_VOP2_SMART1:
> > + case ROCKCHIP_VOP2_ESMART1:
> > + case ROCKCHIP_VOP2_CLUSTER1:
> > + continue;
> > + }
>
>
> Think about this , there maybe other upcoming vop2 base soc, they may only
> have
>
> mirror window Smart1 Esmart1, or Smart1, Esmart1, Esmart2, Cluster1.
>
> I think this should add WIN_FEATURE at the platform description file
> rockchip_vop2_reg.c, then
>
> check the FEATURE to decide whether the driver should give this window a
> special treatment.
>
> this can make one code run for different soc with different platform
> description. or we should add
>
> the same code logic for different soc again and again.

You mean like done in the downstream Kernel? Here indeed we have a
WIN_FEATURE_MIRROR flag added to the platform description. This is then
evaluated with:

static bool vop2_is_mirror_win(struct vop2_win *win)
{
return soc_is_rk3566() && (win->feature & WIN_FEATURE_MIRROR);
}

So a flag is added and afterwards its evaluation is SoC specific. That
doesn't help at all and only obfuscates things.

Besides, experience shows that you can't predict a good abstraction for
future hardware revisions, the hardware guys are just too creative in
creating hardware that breaks existing abstractions.

Sascha

--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |