Date:   Tue, 28 Feb 2023 13:46:20 +0100
From:   Gerd Hoffmann <kraxel@redhat.com>
To:     Rob Clark <robdclark@gmail.com>
Cc:     dri-devel@lists.freedesktop.org, Chia-I Wu <olvaffe@gmail.com>,
        Ryan Neph <ryanneph@chromium.org>,
        Dmitry Osipenko <dmitry.osipenko@collabora.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Clark <robdclark@chromium.org>,
        David Airlie <airlied@redhat.com>,
        Gurchetan Singh <gurchetansingh@chromium.org>,
        "open list:VIRTIO GPU DRIVER" 
        <virtualization@lists.linux-foundation.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3] drm/virtio: Add option to disable KMS support
Message-ID: <20230228124620.pfjvj372rifiljew@sirius.home.kraxel.org>
References: <20230227173800.2809727-1-robdclark@gmail.com>
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  Hi,

> +		if (!vgdev->num_scanouts) {
> +			/*
> +			 * Having an EDID but no scanouts is non-sensical,
> +			 * but it is permitted to have no scanouts and no
> +			 * EDID (in which case DRIVER_MODESET and
> +			 * DRIVER_ATOMIC are not advertised)
> +			 */
> +			if (vgdev->has_edid) {
> +				DRM_ERROR("num_scanouts is zero\n");

That error message isn't very clear.

Also I'd suggest to just drop the edid check.  It's about commands
being supported by the device, not about the actual presence of an EDID
blob, so the check doesn't look very useful to me.

take care,
  Gerd