linux-kernel - [PATCH 1/5] drm/modes: Indicate CEA-861 CE modes to user-space

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Message-Id: <20200413214024.46500-2-dev@pp3345.net>
Date:   Mon, 13 Apr 2020 23:40:22 +0200
From:   Yussuf Khalil <dev@...345.net>
To:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     Yussuf Khalil <dev@...345.net>
Subject: [PATCH 1/5] drm/modes: Indicate CEA-861 CE modes to user-space

Add a new flag to mark modes that are considered a CE mode according to the
CEA-861 specification. Modes without this flag are implicitly considered to
be IT modes.

User-space applications may use this flag to determine possible
implications of using a CE mode (e.g., limited RGB range).

There is no use for this flag inside the kernel, so we set it only when
communicating a mode to user-space.

Signed-off-by: Yussuf Khalil <dev@...345.net>
---
 drivers/gpu/drm/drm_modes.c | 14 ++++++++++++++
 include/uapi/drm/drm_mode.h |  2 ++
 2 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index d4d64518e11b..0d8a032f437d 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1973,6 +1973,14 @@ void drm_mode_convert_to_umode(struct drm_mode_modeinfo *out,
 		break;
 	}
 
+	if (drm_match_cea_mode(in) > 1) {
+		/*
+		 * All modes in CTA-861-G Table 1 are CE modes, except 640x480p
+		 * (VIC 1).
+		 */
+		out->flags |= DRM_MODE_FLAG_CEA_861_CE_MODE;
+	}
+
 	strncpy(out->name, in->name, DRM_DISPLAY_MODE_LEN);
 	out->name[DRM_DISPLAY_MODE_LEN-1] = 0;
 }
@@ -2045,6 +2053,12 @@ int drm_mode_convert_umode(struct drm_device *dev,
 		return -EINVAL;
 	}
 
+	/*
+	 * The CEA-861 CE mode flag is purely informational and intended for
+	 * userspace only.
+	 */
+	out->flags &= ~DRM_MODE_FLAG_CEA_861_CE_MODE;
+
 	out->status = drm_mode_validate_driver(dev, out);
 	if (out->status != MODE_OK)
 		return -EINVAL;
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 735c8cfdaaa1..5e78b350b2e2 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -124,6 +124,8 @@ extern "C" {
 #define  DRM_MODE_FLAG_PIC_AR_256_135 \
 			(DRM_MODE_PICTURE_ASPECT_256_135<<19)
 
+#define DRM_MODE_FLAG_CEA_861_CE_MODE (1<<23)
+
 #define  DRM_MODE_FLAG_ALL	(DRM_MODE_FLAG_PHSYNC |		\
 				 DRM_MODE_FLAG_NHSYNC |		\
 				 DRM_MODE_FLAG_PVSYNC |		\
-- 
2.26.0