linux-kernel - Re: [PATCH v2 3/3] drm/ingenic: ipu: Only enable clock when needed

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Date:   Tue, 4 Aug 2020 11:31:29 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Cc:     Sam Ravnborg <sam@...nborg.org>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, od@...c.me,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] drm/ingenic: ipu: Only enable clock when needed

On Thu, Jul 30, 2020 at 06:21:05PM +0200, Paul Cercueil wrote:
>
>
> Le jeu. 30 juil. 2020 à 17:29, Sam Ravnborg <sam@...nborg.org> a écrit :
> > On Thu, Jul 30, 2020 at 04:48:30PM +0200, Paul Cercueil wrote:
> > >  Instead of keeping the IPU clock enabled constantly, enable and
> > > disable
> > >  it on demand, when the IPU plane is used. That way, we won't use any
> > >  extra power when the IPU is not used.
> > >
> > >  v2: Explain the reason of this patch
> > >
> > >  Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> > Reviewed-by: Sam Ravnborg <sam@...nborg.org>
> >
> > And thanks for the quick update!
>
> Pushed to drm-misc-next. Thanks!

Hi Paul,

Maybe I'm mixing up people, but iirc you're the one very much interested
in running fbdev userspace. Did you think about building up a set of
regression tests in igt (which we could eventually even run on something
like vkms for hw-free regression testing) so that we make sure fbdev keeps
wroking?

Defacto drm_fb_helper.c has become the fbdev reference implementation
already anyway (e.g. with stuff like stanardizing vblank waiting
behaviour), so this would only be the next logical step.

Also adding Bart.

Cheers, Daniel


>
> Cheers,
> -Paul
>
> >
> >     Sam
> >
> > >  ---
> > >   drivers/gpu/drm/ingenic/ingenic-ipu.c | 23 ++++++++++++++++++++---
> > >   1 file changed, 20 insertions(+), 3 deletions(-)
> > >
> > >  diff --git a/drivers/gpu/drm/ingenic/ingenic-ipu.c
> > > b/drivers/gpu/drm/ingenic/ingenic-ipu.c
> > >  index 7dd2a6ae4994..fc8c6e970ee3 100644
> > >  --- a/drivers/gpu/drm/ingenic/ingenic-ipu.c
> > >  +++ b/drivers/gpu/drm/ingenic/ingenic-ipu.c
> > >  @@ -49,6 +49,7 @@ struct ingenic_ipu {
> > >           struct regmap *map;
> > >           struct clk *clk;
> > >           const struct soc_info *soc_info;
> > >  +        bool clk_enabled;
> > >
> > >           unsigned int num_w, num_h, denom_w, denom_h;
> > >
> > >  @@ -288,12 +289,23 @@ static void
> > > ingenic_ipu_plane_atomic_update(struct drm_plane *plane,
> > >           const struct drm_format_info *finfo;
> > >           u32 ctrl, stride = 0, coef_index = 0, format = 0;
> > >           bool needs_modeset, upscaling_w, upscaling_h;
> > >  +        int err;
> > >
> > >           if (!state || !state->fb)
> > >                   return;
> > >
> > >           finfo = drm_format_info(state->fb->format->format);
> > >
> > >  +        if (!ipu->clk_enabled) {
> > >  +                err = clk_enable(ipu->clk);
> > >  +                if (err) {
> > >  +                        dev_err(ipu->dev, "Unable to enable clock: %d\n", err);
> > >  +                        return;
> > >  +                }
> > >  +
> > >  +                ipu->clk_enabled = true;
> > >  +        }
> > >  +
> > >           /* Reset all the registers if needed */
> > >           needs_modeset = drm_atomic_crtc_needs_modeset(state->crtc->state);
> > >           if (needs_modeset) {
> > >  @@ -578,6 +590,11 @@ static void
> > > ingenic_ipu_plane_atomic_disable(struct drm_plane *plane,
> > >           regmap_clear_bits(ipu->map, JZ_REG_IPU_CTRL, JZ_IPU_CTRL_CHIP_EN);
> > >
> > >           ingenic_drm_plane_disable(ipu->master, plane);
> > >  +
> > >  +        if (ipu->clk_enabled) {
> > >  +                clk_disable(ipu->clk);
> > >  +                ipu->clk_enabled = false;
> > >  +        }
> > >   }
> > >
> > >   static const struct drm_plane_helper_funcs
> > > ingenic_ipu_plane_helper_funcs = {
> > >  @@ -761,9 +778,9 @@ static int ingenic_ipu_bind(struct device *dev,
> > > struct device *master, void *d)
> > >           drm_object_attach_property(&plane->base, ipu->sharpness_prop,
> > >                                      ipu->sharpness);
> > >
> > >  -        err = clk_prepare_enable(ipu->clk);
> > >  +        err = clk_prepare(ipu->clk);
> > >           if (err) {
> > >  -                dev_err(dev, "Unable to enable clock\n");
> > >  +                dev_err(dev, "Unable to prepare clock\n");
> > >                   return err;
> > >           }
> > >
> > >  @@ -775,7 +792,7 @@ static void ingenic_ipu_unbind(struct device
> > > *dev,
> > >   {
> > >           struct ingenic_ipu *ipu = dev_get_drvdata(dev);
> > >
> > >  -        clk_disable_unprepare(ipu->clk);
> > >  +        clk_unprepare(ipu->clk);
> > >   }
> > >
> > >   static const struct component_ops ingenic_ipu_ops = {
> > >  --
> > >  2.27.0
>
>

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch