Re: [PATCH v5 20/22] drm/vc4: vec: Convert to the new TV mode property

From: Mateusz Kwiatkowski <kfyatek@gmail.com>
To: Maxime Ripard <maxime@cerno.tech>,
	Karol Herbst <kherbst@redhat.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
	Daniel Vetter <daniel@ffwll.ch>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	David Airlie <airlied@linux.ie>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Lyude Paul <lyude@redhat.com>, Maxime Ripard <mripard@kernel.org>,
	Emma Anholt <emma@anholt.net>, Chen-Yu Tsai <wens@csie.org>,
	Samuel Holland <samuel@sholland.org>,
	Ben Skeggs <bskeggs@redhat.com>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: "Dom Cobley" <dom@raspberrypi.com>,
	linux-sunxi@lists.linux.dev,
	"Dave Stevenson" <dave.stevenson@raspberrypi.com>,
	"Noralf Trønnes" <noralf@tronnes.org>,
	intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	nouveau@lists.freedesktop.org,
	"Geert Uytterhoeven" <geert@linux-m68k.org>,
	linux-arm-kernel@lists.infradead.org,
	dri-devel@lists.freedesktop.org,
	"Hans de Goede" <hdegoede@redhat.com>,
	"Phil Elwell" <phil@raspberrypi.com>
Subject: Re: [PATCH v5 20/22] drm/vc4: vec: Convert to the new TV mode property
Date: Sun, 16 Oct 2022 20:56:22 +0200	[thread overview]
Message-ID: <0f2beec2-ae8e-5579-f0b6-a73d9dae1af4@gmail.com> (raw)
In-Reply-To: <c1949248-fb40-682c-492e-bafbd915cee3@gmail.com>

Hi Maxime,

Urgh. I cannot send e-mails apparently today, as I removed the second half of
the previous message. Here goes:

> @@ -454,13 +563,6 @@ static int vc4_vec_encoder_atomic_check(struct drm_encoder *encoder,
>  					struct drm_connector_state *conn_state)
>  {
>  	const struct drm_display_mode *mode = &crtc_state->adjusted_mode;

You could add here something like:

+	const struct vc4_vec_tv_mode *tv_mode =
+		vc4_vec_tv_mode_lookup(conn_state->tv.mode);
+
+	if (!tv_mode)
+		return -EINVAL;

This should explicitly make it impossible to enter the equivalent condition in
vc4_vec_encoder_enable() that causes the problem mentioned in the previous
e-mail.

This is probably basically impossible already, but I triggered that when testing
a follow-up change I'd like to post shortly.

> -	const struct vc4_vec_tv_mode *vec_mode;
> -
> -	vec_mode = &vc4_vec_tv_modes[conn_state->tv.legacy_mode];
> -
> -	if (conn_state->crtc &&
> -	    !drm_mode_equal(vec_mode->mode, &crtc_state->adjusted_mode))
> -		return -EINVAL;

If you're removing the reference mode, then I think you should at least add
checks that the crtc_clock is set to 13.5 MHz (it's otherwise ignored) and that
crtc_htotal is either 858 or 864 (using a switch over reference_mode->htotal as
I proposed in my comment to patch 19/22 would double as such check), as all
other values causes VEC to output garbage.

Best regards,
Mateusz Kwiatkowski

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