8714c0cecf
Add display_timing structure and the according helper functions. This allows
the description of a display via its supported timing parameters.
Also, add helper functions to convert from display timings to a generic videomode
structure.
The struct display_timing specifies all needed parameters to describe the signal
properties of a display in one mode. This includes
- ranges for signals that may have min-, max- and typical values
- single integers for signals that can be on, off or are ignored
- booleans for signals that are either on or off
As a display may support multiple modes like this, a struct display_timings is
added, that holds all given struct display_timing pointers and declares the
native mode of the display.
Although a display may state that a signal can be in a range, it is driven with
fixed values that indicate a videomode. Therefore graphic drivers don't need all
the information of struct display_timing, but would generate a videomode from
the given set of supported signal timings and work with that.
The video subsystems all define their own structs that describe a mode and work
with that (e.g. fb_videomode or drm_display_mode). To slowly replace all those
various structures and allow code reuse across those subsystems, add struct
videomode as a generic description.
This patch only includes the most basic fields in struct videomode. All missing
fields that are needed to have a really generic video mode description can be
added at a later stage.
Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Reviewed-by: Thierry Reding <thierry.reding@avionic-design.de>
Acked-by: Thierry Reding <thierry.reding@avionic-design.de>
Tested-by: Thierry Reding <thierry.reding@avionic-design.de>
Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Afzal Mohammed <Afzal@ti.com>
Tested-by: Rob Clark <robclark@gmail.com>
Tested-by: Leela Krishna Amudala <leelakrishna.a@gmail.com>
124 lines
3.5 KiB
C
124 lines
3.5 KiB
C
/*
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* Copyright 2012 Steffen Trumtrar <s.trumtrar@pengutronix.de>
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*
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* description of display timings
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*
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* This file is released under the GPLv2
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*/
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#ifndef __LINUX_DISPLAY_TIMING_H
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#define __LINUX_DISPLAY_TIMING_H
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#include <linux/bitops.h>
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#include <linux/types.h>
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/* VESA display monitor timing parameters */
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#define VESA_DMT_HSYNC_LOW BIT(0)
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#define VESA_DMT_HSYNC_HIGH BIT(1)
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#define VESA_DMT_VSYNC_LOW BIT(2)
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#define VESA_DMT_VSYNC_HIGH BIT(3)
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/* display specific flags */
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#define DISPLAY_FLAGS_DE_LOW BIT(0) /* data enable flag */
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#define DISPLAY_FLAGS_DE_HIGH BIT(1)
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#define DISPLAY_FLAGS_PIXDATA_POSEDGE BIT(2) /* drive data on pos. edge */
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#define DISPLAY_FLAGS_PIXDATA_NEGEDGE BIT(3) /* drive data on neg. edge */
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#define DISPLAY_FLAGS_INTERLACED BIT(4)
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#define DISPLAY_FLAGS_DOUBLESCAN BIT(5)
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/*
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* A single signal can be specified via a range of minimal and maximal values
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* with a typical value, that lies somewhere inbetween.
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*/
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struct timing_entry {
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u32 min;
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u32 typ;
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u32 max;
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};
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enum timing_entry_index {
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TE_MIN = 0,
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TE_TYP = 1,
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TE_MAX = 2,
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};
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/*
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* Single "mode" entry. This describes one set of signal timings a display can
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* have in one setting. This struct can later be converted to struct videomode
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* (see include/video/videomode.h). As each timing_entry can be defined as a
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* range, one struct display_timing may become multiple struct videomodes.
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*
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* Example: hsync active high, vsync active low
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*
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* Active Video
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* Video ______________________XXXXXXXXXXXXXXXXXXXXXX_____________________
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* |<- sync ->|<- back ->|<----- active ----->|<- front ->|<- sync..
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* | | porch | | porch |
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*
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* HSync _|¯¯¯¯¯¯¯¯¯¯|___________________________________________|¯¯¯¯¯¯¯¯¯
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*
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* VSync ¯|__________|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯|_________
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*/
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struct display_timing {
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struct timing_entry pixelclock;
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struct timing_entry hactive; /* hor. active video */
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struct timing_entry hfront_porch; /* hor. front porch */
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struct timing_entry hback_porch; /* hor. back porch */
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struct timing_entry hsync_len; /* hor. sync len */
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struct timing_entry vactive; /* ver. active video */
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struct timing_entry vfront_porch; /* ver. front porch */
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struct timing_entry vback_porch; /* ver. back porch */
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struct timing_entry vsync_len; /* ver. sync len */
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unsigned int dmt_flags; /* VESA DMT flags */
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unsigned int data_flags; /* video data flags */
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};
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/*
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* This describes all timing settings a display provides.
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* The native_mode is the default setting for this display.
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* Drivers that can handle multiple videomodes should work with this struct and
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* convert each entry to the desired end result.
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*/
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struct display_timings {
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unsigned int num_timings;
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unsigned int native_mode;
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struct display_timing **timings;
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};
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/* get value specified by index from struct timing_entry */
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static inline u32 display_timing_get_value(const struct timing_entry *te,
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enum timing_entry_index index)
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{
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switch (index) {
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case TE_MIN:
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return te->min;
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break;
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case TE_TYP:
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return te->typ;
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break;
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case TE_MAX:
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return te->max;
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break;
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default:
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return te->typ;
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}
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}
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/* get one entry from struct display_timings */
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static inline struct display_timing *display_timings_get(const struct
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display_timings *disp,
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unsigned int index)
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{
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if (disp->num_timings > index)
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return disp->timings[index];
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else
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return NULL;
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}
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void display_timings_release(struct display_timings *disp);
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#endif
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