The docs are wrong for the DRM implementation.The docs say:So, M means use a formula. Lack of M means look up the mode "from a table". Not quite clear what the table is, but I'd assumed this was using some standards.If 'M' is specified in the mode_option argument (after <yres> and before <bpp> and <refresh>, if specified) the timings will be calculated using VESA(TM) Coordinated Video Timings instead of looking up the mode from a table. If 'R' is specified, do a 'reduced blanking' calculation for digital displays. If 'i' is specified, calculate for an interlaced mode. And if 'm' is specified, add margins to the calculation (1.8% of xres rounded down to 8 pixels and 1.8% of yres).
video= is inherited from fbdev.
fbdev parsing of "video=" is in fb_find_mode, and that compares the mode name or resolution against modedb (or a table passed in)
DRM parsing is in drm_mode_create_from_cmdline_mode, and uses GTF if the "M" flag isn't given to denote CVT.
Statistics: Posted by 6by9 — Wed Jan 24, 2024 12:43 pm