[PATCH] drm/crtc: Add a helper func to get a registered crtc from its index

[Xinliang Liu]

On 26 August 2015 at 19:04, Thierry Reding <thierry.reding at gmail.com> wrote:

> On Tue, Aug 25, 2015 at 11:36:18AM +0200, Daniel Vetter wrote:
> > On Tue, Aug 25, 2015 at 11:13:51AM +0800, Xinliang Liu wrote:
> > > This patch add a helper func to get a registered crtc from its index.
> > > In some case, where we know the crtc's index and we want to know the
> > > crtc too.
> > >
> > > For example, the enable_vblank func of struct drm_driver:
> > > In the implementation of this func, we know the index of the crtc but
> > > we want to know the crtc. This helper func can get the crtc easily.
> > > A sample impelmentation of enable_vblank is as shown as bellow:
> > >
> > > int hisi_drm_crtc_enable_vblank(struct drm_device *dev, int c)
> > > {
> > >     struct drm_crtc *crtc = drm_get_crtc_from_index(dev, c);
> > >     struct hisi_crtc *hcrtc = to_hisi_crtc(crtc);
> > >     struct hisi_crtc_ops *ops = hcrtc->ops;
> > >     int ret = 0;
> > >
> > >     if (ops->enable_vblank)
> > >             ret = ops->enable_vblank(hcrtc);
> > >
> > >     return ret;
> > > }
> > >
> > > Signed-off-by: Xinliang Liu <xinliang.liu at linaro.org>
> >
> > Yeah unfortunately drm_irq.c is still stick in the old pre-KMS days. I
> > think we should go a bit further here though to allow new drivers to be
> > completely free of int pipe:
>
> Of course you meant to say /unsigned/ int pipe =)
>
> > - add a new array pointer dev->mode_conifg.crtc_arr, which is
> >   (re-)allocated in drm_crtc_init_with_planes. Then a pipe->crtc lookup
> >   will be just
> >
> >       crtc = dev->mode_config.crtc_arr[pipe];
> >
> > - add new hooks for vblank handling int drm_crtc_helper_funcs for
> >   enable_vblanke, disable_vblank, get_vblank_timestamp and
> get_scanoutpos.
> >   Ofc also anotate the docs for the existing hooks and make it clear new
> >   drivers should use the new ones. Ofc these new hooks should directly
> >   take a struct drm_crtc * instead of inte pipe.
>
> I have a couple patches to address this partially, which came about as a
> result of the int crtc/crtc_id/pipe/whatever -> unsigned int pipe
> conversion work that I've been doing.
>
Hi Thierry, I wonder what your patches look like. Could you share them to
me.


> > - change the code in drm_irq.c to wrap all callbacks and first check
> >   whether the new ones are there and only if that's not the case call the
> >   old ones.
> >
> > With these changes drivers can be completely free of int pipe and use
> > struct drm_crtc exclusivly I think, and the mess would be fully
> restricted
> > to drm_irq.c.
>
> I like the idea of moving the callbacks to drm_crtc_helper_funcs. That
> allows us to introduce this step by step, without a flag date when every
> driver needs to switch the drm_driver functions over.
>
> Thierry
>
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