linux-kernel - Re: [PATCH v2 05/12] drm/sun4i: engine: Add a VBLANK quirk callback

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Date:   Tue, 19 Dec 2017 13:09:33 +0800
From:   Chen-Yu Tsai <wens@...e.org>
To:     Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:     Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>, Chen-Yu Tsai <wens@...e.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Neil Armstrong <narmstrong@...libre.com>, thomas@...sch.nl
Subject: Re: [PATCH v2 05/12] drm/sun4i: engine: Add a VBLANK quirk callback

On Mon, Dec 18, 2017 at 10:57 PM, Maxime Ripard
<maxime.ripard@...e-electrons.com> wrote:
> In some cases, the display engine needs to apply some quirks during the
> VBLANK event. In the Display Engine 1.0 case for example, we can only
> disable the frontend once the backend has been, which is at VBLANK.
>
> Let's introduce a callback that can be implemented by the various engines.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
> ---
>  drivers/gpu/drm/sun4i/sun4i_tcon.c   |  4 ++++
>  drivers/gpu/drm/sun4i/sunxi_engine.h | 12 ++++++++++++
>  2 files changed, 16 insertions(+)
>
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index e122f5b2a395..55f54b54293c 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -368,6 +368,7 @@ static irqreturn_t sun4i_tcon_handler(int irq, void *private)
>         struct sun4i_tcon *tcon = private;
>         struct drm_device *drm = tcon->drm;
>         struct sun4i_crtc *scrtc = tcon->crtc;
> +       struct sunxi_engine *engine = scrtc->engine;
>         unsigned int status;
>
>         regmap_read(tcon->regs, SUN4I_TCON_GINT0_REG, &status);
> @@ -385,6 +386,9 @@ static irqreturn_t sun4i_tcon_handler(int irq, void *private)
>                            SUN4I_TCON_GINT0_VBLANK_INT(1),
>                            0);
>
> +       if (engine->ops->vblank_quirk)
> +               engine->ops->vblank_quirk(engine);
> +
>         return IRQ_HANDLED;
>  }
>
> diff --git a/drivers/gpu/drm/sun4i/sunxi_engine.h b/drivers/gpu/drm/sun4i/sunxi_engine.h
> index da2dd36dfbb6..b810c26d78bb 100644
> --- a/drivers/gpu/drm/sun4i/sunxi_engine.h
> +++ b/drivers/gpu/drm/sun4i/sunxi_engine.h
> @@ -86,6 +86,18 @@ struct sunxi_engine_ops {
>         struct drm_plane **(*layers_init)(struct drm_device *drm,
>                                           struct sunxi_engine *engine);
>
> +       /**
> +        * @vblank_quirk:
> +        *
> +        * This callback is used to implement backend-specific

                                                ^ engine

Otherwise,

Reviewed-by: Chen-Yu Tsai <wens@...e.org>

> +        * behaviour part of the VBLANK event. It is run with all the
> +        * constraints of an interrupt (can't sleep, all local
> +        * interrupts disabled) and therefore should be as fast as
> +        * possible.
> +        *
> +        * This function is optional.
> +        */
> +       void (*vblank_quirk)(struct sunxi_engine *engine);
>  };
>
>  /**
> --
> git-series 0.9.1