On Tue, 19 May 2026, Javier Martinez Canillas <[email protected]> wrote: > 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 <drm/display/drm_hdmi_helper.h> header correspond > to maximum TMDS character rates defined by each HDMI specification version: > > - DRM_HDMI_TMDS_CHAR_RATE_MIN: 25 MHz (minimum for all versions) > - DRM_HDMI_TMDS_CHAR_RATE_MAX_1_0: 165 MHz (HDMI 1.0 maximum) > - DRM_HDMI_TMDS_CHAR_RATE_MAX_1_3: 340 MHz (HDMI 1.3 maximum) > - DRM_HDMI_TMDS_CHAR_RATE_MAX_2_0: 600 MHz (HDMI 2.0 maximum) > > Suggested-by: Maxime Ripard <[email protected]> > Signed-off-by: Javier Martinez Canillas <[email protected]> > --- > > include/drm/display/drm_hdmi_helper.h | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/include/drm/display/drm_hdmi_helper.h > b/include/drm/display/drm_hdmi_helper.h > index 9c31ed90516b..0ee246ff82e0 100644 > --- a/include/drm/display/drm_hdmi_helper.h > +++ b/include/drm/display/drm_hdmi_helper.h > @@ -5,6 +5,12 @@ > > #include <linux/hdmi.h> > > +/* HDMI spec TMDS character rate limits (in Hz) */ > +#define DRM_HDMI_TMDS_CHAR_RATE_MIN 25000000 > +#define DRM_HDMI_TMDS_CHAR_RATE_MAX_1_0 165000000 > +#define DRM_HDMI_TMDS_CHAR_RATE_MAX_1_3 340000000 > +#define DRM_HDMI_TMDS_CHAR_RATE_MAX_2_0 600000000
Usually everything in DRM is in kHz, and Hz is the exception. I'm also not sure the 1_0, 1_3, and 2_0 really help anyone reading the code. I won't remember what they mean in Hz or kHz, and I'll have to look them up every single time. BR, Jani. > + > struct drm_connector; > struct drm_connector_state; > struct drm_display_mode; -- Jani Nikula, Intel
