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panel: Lightweight support of get_modes()

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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)
2026-01-05 10:36:27 +01:00
committed by Tom Rini
parent 60f5170c1f
commit 36829e951b
2 changed files with 104 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
drivers/video/panel-uclass.c
View File

@@ -37,15 +37,47 @@ int panel_set_backlight(struct udevice *dev, int percent)
return ops->set_backlight(dev, percent);
}
static void drm_mode_to_display_timing(const struct drm_display_mode *mode,
struct display_timing *timing)
{
timing->pixelclock.typ = mode->clock * 1000; /* kHz to Hz */
timing->hactive.typ = mode->hdisplay;
timing->hfront_porch.typ = mode->hsync_start - mode->hdisplay;
timing->hsync_len.typ = mode->hsync_end - mode->hsync_start;
timing->hback_porch.typ = mode->htotal - mode->hsync_end;
timing->vactive.typ = mode->vdisplay;
timing->vfront_porch.typ = mode->vsync_start - mode->vdisplay;
timing->vsync_len.typ = mode->vsync_end - mode->vsync_start;
timing->vback_porch.typ = mode->vtotal - mode->vsync_end;
/* DRM_MODE_FLAG_* defines are already mapped to u-boot DISPLAY_FLAGS */
timing->flags = mode->flags;
}
int panel_get_display_timing(struct udevice *dev,
struct display_timing *timings)
{
struct panel_ops *ops = panel_get_ops(dev);
const struct drm_display_mode *modes;
int ret = -ENOSYS;
if (!ops->get_display_timing)
return -ENOSYS;
if (ops->get_display_timing) {
ret = ops->get_display_timing(dev, timings);
if (ret != -ENODEV)
return ret;
}
return ops->get_display_timing(dev, timings);
if (!ops->get_modes)
return ret;
ret = ops->get_modes(dev, &modes);
if (ret < 0)
return ret;
else if (ret == 0)
return -ENODEV;
drm_mode_to_display_timing(&modes[0], timings);
return 0;
}
UCLASS_DRIVER(panel) = {

69
include/panel.h
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)