video/hdmi: Add common TMDS character rate constants

Several DRM drivers already define their own constants for minimum and
maximum TMDS character rates.

By defining common rate constants in a shared header, drivers can just use
them instead of having driver local define macros or use magic numbers.

The values defined in the <linux/hdmi.h> header correspond to maximum TMDS
character rates defined by each HDMI specification version:

  - HDMI_TMDS_CHAR_RATE_MIN_HZ:     25 MHz (minimum for all versions)
  - HDMI_1_0_TMDS_CHAR_RATE_MAX_HZ: 165 MHz (HDMI 1.0 maximum)
  - HDMI_1_3_TMDS_CHAR_RATE_MAX_HZ: 340 MHz (HDMI 1.3 maximum)
  - HDMI_2_0_TMDS_CHAR_RATE_MAX_HZ: 600 MHz (HDMI 2.0 maximum)

Suggested-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://patch.msgid.link/20260520144424.1633354-2-javierm@redhat.com
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>

diff --git a/include/linux/hdmi.h b/include/linux/hdmi.h
index 96bda41d9148c8c17dda1f23d5134c102495476c..8dab78e1f61bd9f8688f8b6236865177f4d8ab54 100644 (file)
--- a/include/linux/hdmi.h
+++ b/include/linux/hdmi.h
@@ -50,6 +50,12 @@ enum hdmi_infoframe_type {
        HDMI_INFOFRAME_TYPE_DRM = 0x87,
 };
 
+/* HDMI spec maximum TMDS character rates, in Hz */
+#define HDMI_TMDS_CHAR_RATE_MIN_HZ         25000000
+#define HDMI_1_0_TMDS_CHAR_RATE_MAX_HZ    165000000
+#define HDMI_1_3_TMDS_CHAR_RATE_MAX_HZ    340000000
+#define HDMI_2_0_TMDS_CHAR_RATE_MAX_HZ    600000000
+
 #define HDMI_IEEE_OUI 0x000c03
 #define HDMI_FORUM_IEEE_OUI 0xc45dd8
 #define HDMI_INFOFRAME_HEADER_SIZE  4