panel: Lightweight support of get_modes()

Linux uses get_modes() to fetch all available panel modes from the
driver. This is also used to fetch the modes from Linux's simple panel
implementation where a list of drm_display_mode structs is used to
define the different possible panels.

To make our work easier, create a compatible way of fetching and
defining these modes in u-boot. get_modes() fetches the available modes
from the panel driver. The get_display_timing() call maps the
drm_display_mode properties to the display_timing struct. This call now
uses whatever panel operation is available, get_display_timing() or
get_modes().

Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Markus Schneider-Pargmann (TI.com) <msp@baylibre.com>
This commit is contained in:
Markus Schneider-Pargmann (TI.com)
2026-01-16 09:07:28 -06:00
committed by Tom Rini
parent 60f5170c1f
commit 36829e951b
2 changed files with 104 additions and 3 deletions
+69
View File
@@ -7,6 +7,62 @@
#ifndef _PANEL_H
#define _PANEL_H
#include <video.h>
#include <fdtdec.h>
/* DRM mode flags mapped to U-Boot DISPLAY_FLAGS for direct compatibility */
#define DRM_MODE_FLAG_NHSYNC DISPLAY_FLAGS_HSYNC_LOW
#define DRM_MODE_FLAG_PHSYNC DISPLAY_FLAGS_HSYNC_HIGH
#define DRM_MODE_FLAG_NVSYNC DISPLAY_FLAGS_VSYNC_LOW
#define DRM_MODE_FLAG_PVSYNC DISPLAY_FLAGS_VSYNC_HIGH
#define DRM_MODE_FLAG_INTERLACE DISPLAY_FLAGS_INTERLACED
#define DRM_MODE_FLAG_DBLSCAN DISPLAY_FLAGS_DOUBLESCAN
#define DRM_MODE_FLAG_DBLCLK DISPLAY_FLAGS_DOUBLECLK
/**
* struct drm_display_mode - DRM kernel-internal display mode structure
* simplified for U-Boot
* @hdisplay: horizontal display size
* @hsync_start: horizontal sync start
* @hsync_end: horizontal sync end
* @htotal: horizontal total size
* @vdisplay: vertical display size
* @vsync_start: vertical sync start
* @vsync_end: vertical sync end
* @vtotal: vertical total size
*
* The horizontal and vertical timings are defined per the following diagram.
*
* ::
*
*
* Active Front Sync Back
* Region Porch Porch
* <-----------------------><----------------><-------------><-------------->
* //////////////////////|
* ////////////////////// |
* ////////////////////// |.................. ................
* _______________
* <----- [hv]display ----->
* <------------- [hv]sync_start ------------>
* <--------------------- [hv]sync_end --------------------->
* <-------------------------------- [hv]total ----------------------------->*
*/
struct drm_display_mode {
unsigned int clock; /* in kHz */
u16 hdisplay;
u16 hsync_start;
u16 hsync_end;
u16 htotal;
u16 vdisplay;
u16 vsync_start;
u16 vsync_end;
u16 vtotal;
u32 flags;
};
struct panel_ops {
/**
* enable_backlight() - Enable the panel backlight
@@ -34,6 +90,19 @@ struct panel_ops {
*/
int (*get_display_timing)(struct udevice *dev,
struct display_timing *timing);
/**
* get_modes() - Get display modes from panel
*
* Returns an array of display modes supported by the panel.
* Similar to Linux's drm_panel_funcs->get_modes().
*
* @dev: Panel device
* @modes: Pointer to an array of modes
* @return number of modes if OK, -ve on error
*/
int (*get_modes)(struct udevice *dev,
const struct drm_display_mode **modes);
};
#define panel_get_ops(dev) ((struct panel_ops *)(dev)->driver->ops)