Hi Laurent,

On Tue, Sep 04, 2018 at 03:10:17PM +0300, Laurent Pinchart wrote:
> The rcar_du_crtc_get() function is always immediately followed by a call
> to rcar_du_crtc_setup(). Call the later from the former to simplify the
> code, and add a comment to explain how the get and put calls are
> balanced.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+rene...@ideasonboard.com>
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 107 
> +++++++++++++++++----------------
>  1 file changed, 56 insertions(+), 51 deletions(-)
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c 
> b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> index 4c9572d7ea89..1d81eb244441 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> @@ -66,39 +66,6 @@ static void rcar_du_crtc_clr_set(struct rcar_du_crtc 
> *rcrtc, u32 reg,
>       rcar_du_write(rcdu, rcrtc->mmio_offset + reg, (value & ~clr) | set);
>  }
>
> -static int rcar_du_crtc_get(struct rcar_du_crtc *rcrtc)
> -{
> -     int ret;
> -
> -     ret = clk_prepare_enable(rcrtc->clock);
> -     if (ret < 0)
> -             return ret;
> -
> -     ret = clk_prepare_enable(rcrtc->extclock);
> -     if (ret < 0)
> -             goto error_clock;
> -
> -     ret = rcar_du_group_get(rcrtc->group);
> -     if (ret < 0)
> -             goto error_group;
> -
> -     return 0;
> -
> -error_group:
> -     clk_disable_unprepare(rcrtc->extclock);
> -error_clock:
> -     clk_disable_unprepare(rcrtc->clock);
> -     return ret;
> -}
> -
> -static void rcar_du_crtc_put(struct rcar_du_crtc *rcrtc)

For what I see, rcar_du_crtc_stop() is also called once just before
_put(). Have you considered doing with them what you've done with
_get() and _setup() ?

Thanks
   j

> -{
> -     rcar_du_group_put(rcrtc->group);
> -
> -     clk_disable_unprepare(rcrtc->extclock);
> -     clk_disable_unprepare(rcrtc->clock);
> -}
> -
>  /* 
> -----------------------------------------------------------------------------
>   * Hardware Setup
>   */
> @@ -546,6 +513,51 @@ static void rcar_du_crtc_setup(struct rcar_du_crtc 
> *rcrtc)
>       drm_crtc_vblank_on(&rcrtc->crtc);
>  }
>
> +static int rcar_du_crtc_get(struct rcar_du_crtc *rcrtc)
> +{
> +     int ret;
> +
> +     /*
> +      * Guard against double-get, as the function is called from both the
> +      * .atomic_enable() and .atomic_begin() handlers.
> +      */
> +     if (rcrtc->initialized)
> +             return 0;
> +
> +     ret = clk_prepare_enable(rcrtc->clock);
> +     if (ret < 0)
> +             return ret;
> +
> +     ret = clk_prepare_enable(rcrtc->extclock);
> +     if (ret < 0)
> +             goto error_clock;
> +
> +     ret = rcar_du_group_get(rcrtc->group);
> +     if (ret < 0)
> +             goto error_group;
> +
> +     rcar_du_crtc_setup(rcrtc);
> +     rcrtc->initialized = true;
> +
> +     return 0;
> +
> +error_group:
> +     clk_disable_unprepare(rcrtc->extclock);
> +error_clock:
> +     clk_disable_unprepare(rcrtc->clock);
> +     return ret;
> +}
> +
> +static void rcar_du_crtc_put(struct rcar_du_crtc *rcrtc)
> +{
> +     rcar_du_group_put(rcrtc->group);
> +
> +     clk_disable_unprepare(rcrtc->extclock);
> +     clk_disable_unprepare(rcrtc->clock);
> +
> +     rcrtc->initialized = false;
> +}
> +
>  static void rcar_du_crtc_start(struct rcar_du_crtc *rcrtc)
>  {
>       bool interlaced;
> @@ -639,16 +651,7 @@ static void rcar_du_crtc_atomic_enable(struct drm_crtc 
> *crtc,
>  {
>       struct rcar_du_crtc *rcrtc = to_rcar_crtc(crtc);
>
> -     /*
> -      * If the CRTC has already been setup by the .atomic_begin() handler we
> -      * can skip the setup stage.
> -      */
> -     if (!rcrtc->initialized) {
> -             rcar_du_crtc_get(rcrtc);
> -             rcar_du_crtc_setup(rcrtc);
> -             rcrtc->initialized = true;
> -     }
> -
> +     rcar_du_crtc_get(rcrtc);
>       rcar_du_crtc_start(rcrtc);
>  }
>
> @@ -667,7 +670,6 @@ static void rcar_du_crtc_atomic_disable(struct drm_crtc 
> *crtc,
>       }
>       spin_unlock_irq(&crtc->dev->event_lock);
>
> -     rcrtc->initialized = false;
>       rcrtc->outputs = 0;
>  }
>
> @@ -680,14 +682,17 @@ static void rcar_du_crtc_atomic_begin(struct drm_crtc 
> *crtc,
>
>       /*
>        * If a mode set is in progress we can be called with the CRTC disabled.
> -      * We then need to first setup the CRTC in order to configure planes.
> -      * The .atomic_enable() handler will notice and skip the CRTC setup.
> +      * We thus need to first get and setup the CRTC in order to configure
> +      * planes. We must *not* put the CRTC in .atomic_flush(), as it must be
> +      * kept awake until the .atomic_enable() call that will follow. The get
> +      * operation in .atomic_enable() will in that case be a no-op, and the
> +      * CRTC will be put later in .atomic_disable().
> +      *
> +      * If a mode set is not in progress the CRTC is enabled, and the
> +      * following get call will be a no-op. There is thus no need to belance
> +      * it in .atomic_flush() either.
>        */
> -     if (!rcrtc->initialized) {
> -             rcar_du_crtc_get(rcrtc);
> -             rcar_du_crtc_setup(rcrtc);
> -             rcrtc->initialized = true;
> -     }
> +     rcar_du_crtc_get(rcrtc);
>
>       if (rcar_du_has(rcrtc->group->dev, RCAR_DU_FEATURE_VSP1_SOURCE))
>               rcar_du_vsp_atomic_begin(rcrtc);
> --
> Regards,
>
> Laurent Pinchart
>

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