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To:     Neil Armstrong <narmstrong@baylibre.com>
Cc:     linux-omap@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, khilman@baylibre.com,
        Benoit Parrot <bparrot@ti.com>
References: <20211018142842.2511200-1-narmstrong@baylibre.com>
 <20211018142842.2511200-9-narmstrong@baylibre.com>
From:   Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Subject: Re: [PATCH v6 8/9] drm/omap: add plane_atomic_print_state support
Message-ID: <70a29d4d-eaab-5162-58b7-df9d9d3e7a9b@ideasonboard.com>
Date:   Wed, 27 Oct 2021 15:23:14 +0300
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On 18/10/2021 17:28, Neil Armstrong wrote:
> From: Benoit Parrot <bparrot@ti.com>
> 
> Now that we added specific item to our subclassed drm_plane_state
> we can add omap_plane_atomic_print_state() helper to dump out our own
> driver specific plane state.
> 
> Signed-off-by: Benoit Parrot <bparrot@ti.com>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> ---
>   drivers/gpu/drm/omapdrm/omap_plane.c | 16 ++++++++++++++++
>   1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/gpu/drm/omapdrm/omap_plane.c b/drivers/gpu/drm/omapdrm/omap_plane.c
> index ce5ed45401fb..5001c8354e4f 100644
> --- a/drivers/gpu/drm/omapdrm/omap_plane.c
> +++ b/drivers/gpu/drm/omapdrm/omap_plane.c
> @@ -348,6 +348,21 @@ omap_plane_atomic_duplicate_state(struct drm_plane *plane)
>   	return &state->base;
>   }
>   
> +static void omap_plane_atomic_print_state(struct drm_printer *p,
> +					  const struct drm_plane_state *state)
> +{
> +	struct omap_plane_state *omap_state = to_omap_plane_state(state);
> +
> +	drm_printf(p, "\toverlay=%s\n", omap_state->overlay ?
> +					omap_state->overlay->name : "(null)");
> +	if (omap_state->overlay) {
> +		drm_printf(p, "\t\tidx=%d\n", omap_state->overlay->idx);
> +		drm_printf(p, "\t\toverlay_id=%d\n",
> +			   omap_state->overlay->id);
> +		drm_printf(p, "\t\tcaps=0x%x\n", omap_state->overlay->caps);
> +	}
> +}

This prints:

         overlay=gfx
                 idx=0
                 overlay_id=0
                 caps=0x3e

I'm not sure if some of these details are needed. The name ("gfx") and 
overlay_id refer to the same thing, and while idx is in theory a 
different value, in practice it's always the same as overlay_id. And 
even if it was a different number, I think idx is kind of irrelevant, 
isn't it?

caps can be figured out from the name of the overlay, but perhaps it 
doesn't hurt to print them here. Then again, if none of the other debug 
prints show the cap values (e.g. "requires cap 0x4), maybe printing the 
caps value is not really useful here.

Maybe this could be just a single line, say:

overlay=gfx

or if caps is useful:

overlay=gfx (caps=0x3e)

What do you think?

  Tomi