disp_mode_info_t

Information for a display mode

Synopsis:

#include <mode.h>

typedef struct disp_mode_info {
   short        size;
   disp_mode_t  mode;
   int          xres, yres;
   unsigned     pixel_format;
   unsigned     flags;
   unsigned     crtc_start_gran;
   unsigned     caps;
   union {
       struct {
          short    refresh [DISP_MODE_NUM_REFRESH];
       } fixed;
       struct {
          int      min_vfreq, max_vfreq;
          int      min_hfreq, max_hfreq;
          int      min_pixel_clock;
          int      max_pixel_clock;
          uint8_t  h_granularity;
          uint8_t  v_granularity;
          uint8_t  sync_polarity;
       } generic;
   } u;
   int       num_colors;
   unsigned  crtc_pitch_gran;
} disp_mode_info_t;

Description:

The disp_mode_info_t structure holds information about a display mode. Your driver fills in this structure when the graphics framework calls the get_modeinfo function defined in the disp_modefuncs_t structure.

The members of disp_mode_info_t include:

size

The size of this structure.

mode

The unique mode ID; see the get_modelist function defined in the disp_modefuncs_t structure.

xres, yres

The display dimensions, in pixels.

pixel_format

The frame buffer's pixel format. For more information, see "Pixel formats" in the Writing a Graphics Driver chapter.

flags

Flags that specify various attributes of this mode, selected from the following:

• DISP_MODE_TVOUT -- this mode drives a TV, and not a monitor.
• DISP_MODE_TVOUT_OR_MONITOR -- this mode can drive a TV or a monitor, but not both simultaneously.
• DISP_MODE_TVOUT_WITH_MONITOR -- this mode can drive a TV and a monitor simultaneously.
• DISP_MODE_TVOUT_OVERSCAN -- the overscan goes beyond the edge of the TV (i.e. there are no borders at the edges).
• DISP_MODE_TVOUT_NTSC -- this mode generates NTSC format video signal.
• DISP_MODE_TVOUT_PAL -- this mode generates PAL format video signal.
• DISP_MODE_TVOUT_SECAM -- this mode generates SECAM format video signal.
• DISP_MODE_GENERIC -- this mode is a generic mode. That is, the mode has a given pixel_format but can handle any resolution or refresh rate, within certain constraints. If this flag is set, the members of the u.generic structure are defined. Otherwise, the members of the u.fixed structure are defined.

Note that there's a macro, DISP_TVOUT_STANDARD() that returns just the type of output (PAL, NTSC, SECAM).

crtc_start_gran

The granularity of the frame buffer base address. Values passed in the offset parameter to the set_display_offset() function in the disp_modefuncs_t structure are multiples of this value.

caps

The list of available features:

• DISP_MCAP_SET_DISPLAY_OFFSET -- the display controller can point to different areas of the video RAM. This indicates that its offset into video RAM isn't hard-coded, meaning that it can perform double-buffering operations.
• DISP_MCAP_DPMS_SUPPORTED -- the display supports DPMS (if this bit set), else no support.
• DISP_MCAP_VIRTUAL_PANNING -- the display supports virtual resolutions that are larger than the physical display, and supports "panning" of the physical viewport into the virtual display.

u.fixed.refresh

An array of possible refresh rates (in Hz) for this mode. The size of this array is given by DISP_MODE_NUM_REFRESH (i.e. it's the maximum number of refresh rates that can be supported for a given mode).

u.generic.min_vfreq, u.generic.max_vfreq

The monitor vertical frequency limits, in Hz.

u.generic.min_hfreq, u.generic.max_hfreq

The monitor horizontal frequency limits, in kHz.

u.generic.min_pixel_clock, u.generic.max_pixel_clock

The pixel clock limits, in kHz.

u.generic.h_granularity

The horizontal granularity; X resolution must be a multiple of this.

u.generic.v_granularity

The vertical granularity; Y resolution must be a multiple of this.

num_colors

Defined only if the display format is palette-based. It specifies the maximum palette index that the display can handle. For example, the example 16-color VGA driver sets this to 16.

Classification:

Photon

See also:

disp_modefuncs_t