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Message-Id: <20230920-kms-hdmi-connector-state-v2-7-17932daddd7d@kernel.org>
Date: Wed, 20 Sep 2023 16:35:22 +0200
From: Maxime Ripard <mripard@...nel.org>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>, Emma Anholt <emma@...olt.net>,
Jonathan Corbet <corbet@....net>,
Sandy Huang <hjc@...k-chips.com>,
Heiko Stübner <heiko@...ech.de>,
Chen-Yu Tsai <wens@...e.org>,
Jernej Skrabec <jernej.skrabec@...il.com>,
Samuel Holland <samuel@...lland.org>
Cc: Hans Verkuil <hverkuil@...all.nl>, dri-devel@...ts.freedesktop.org,
linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
linux-rockchip@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
Maxime Ripard <mripard@...nel.org>
Subject: [PATCH RFC v2 07/37] drm/connector: hdmi: Add HDMI compute clock
helper
A lot of HDMI drivers have some variation of the formula to calculate
the TMDS character rate from a mode, but few of them actually take all
parameters into account.
Let's create a helper to provide that rate taking all parameters into
account.
Signed-off-by: Maxime Ripard <mripard@...nel.org>
---
drivers/gpu/drm/drm_connector.c | 31 +++++++++++++++++++++++++++++++
include/drm/drm_connector.h | 5 +++++
2 files changed, 36 insertions(+)
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index b01cb4783ea6..4c1af97971bb 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -2944,6 +2944,37 @@ void drm_connector_update_privacy_screen(const struct drm_connector_state *conne
}
EXPORT_SYMBOL(drm_connector_update_privacy_screen);
+/**
+ * drm_connector_hdmi_compute_mode_clock() - Computes the TMDS Character Rate
+ * @mode: Display mode to compute the clock for
+ * @bpc: Bits per character
+ * @fmt: Output Pixel Format used
+ *
+ * Returns the TMDS Character Rate for a given mode, bpc count and output format.
+ *
+ * RETURNS:
+ * The TMDS Character Rate, in Hertz
+ */
+unsigned long long
+drm_connector_hdmi_compute_mode_clock(const struct drm_display_mode *mode,
+ unsigned int bpc,
+ enum hdmi_colorspace fmt)
+{
+ unsigned long long clock = mode->clock * 1000ULL;
+
+ if (mode->flags & DRM_MODE_FLAG_DBLCLK)
+ clock = clock * 2;
+
+ if (fmt == HDMI_COLORSPACE_YUV422)
+ bpc = 8;
+
+ clock = clock * bpc;
+ do_div(clock, 8);
+
+ return clock;
+}
+EXPORT_SYMBOL(drm_connector_hdmi_compute_mode_clock);
+
int drm_connector_set_obj_prop(struct drm_mode_object *obj,
struct drm_property *property,
uint64_t value)
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index a66cb4e35d7b..d74e9c64ee88 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -38,6 +38,7 @@ struct drm_connector_helper_funcs;
struct drm_modeset_acquire_ctx;
struct drm_device;
struct drm_crtc;
+struct drm_display_mode;
struct drm_encoder;
struct drm_panel;
struct drm_property;
@@ -2115,6 +2116,10 @@ void drm_connector_attach_privacy_screen_properties(struct drm_connector *conn);
void drm_connector_attach_privacy_screen_provider(
struct drm_connector *connector, struct drm_privacy_screen *priv);
void drm_connector_update_privacy_screen(const struct drm_connector_state *connector_state);
+unsigned long long
+drm_connector_hdmi_compute_mode_clock(const struct drm_display_mode *mode,
+ unsigned int bpc,
+ enum hdmi_colorspace fmt);
/**
* struct drm_tile_group - Tile group metadata
--
2.41.0
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