[PATCHv16 2/7] video: add display_timing and videomode
Steffen Trumtrar
s.trumtrar at pengutronix.de
Tue Dec 18 09:04:11 PST 2012
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 at pengutronix.de>
Reviewed-by: Thierry Reding <thierry.reding at avionic-design.de>
Acked-by: Thierry Reding <thierry.reding at avionic-design.de>
Tested-by: Thierry Reding <thierry.reding at avionic-design.de>
Tested-by: Philipp Zabel <p.zabel at pengutronix.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Acked-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
drivers/video/Kconfig | 6 ++
drivers/video/Makefile | 2 +
drivers/video/display_timing.c | 24 ++++++++
drivers/video/videomode.c | 39 +++++++++++++
include/video/display_timing.h | 124 ++++++++++++++++++++++++++++++++++++++++
include/video/videomode.h | 48 ++++++++++++++++
6 files changed, 243 insertions(+)
create mode 100644 drivers/video/display_timing.c
create mode 100644 drivers/video/videomode.c
create mode 100644 include/video/display_timing.h
create mode 100644 include/video/videomode.h
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index d08d799..2a23b18 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -33,6 +33,12 @@ config VIDEO_OUTPUT_CONTROL
This framework adds support for low-level control of the video
output switch.
+config DISPLAY_TIMING
+ bool
+
+config VIDEOMODE
+ bool
+
menuconfig FB
tristate "Support for frame buffer devices"
---help---
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index 23e948e..fc30439 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -167,3 +167,5 @@ obj-$(CONFIG_FB_VIRTUAL) += vfb.o
#video output switch sysfs driver
obj-$(CONFIG_VIDEO_OUTPUT_CONTROL) += output.o
+obj-$(CONFIG_DISPLAY_TIMING) += display_timing.o
+obj-$(CONFIG_VIDEOMODE) += videomode.o
diff --git a/drivers/video/display_timing.c b/drivers/video/display_timing.c
new file mode 100644
index 0000000..5e1822c
--- /dev/null
+++ b/drivers/video/display_timing.c
@@ -0,0 +1,24 @@
+/*
+ * generic display timing functions
+ *
+ * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar at pengutronix.de>, Pengutronix
+ *
+ * This file is released under the GPLv2
+ */
+
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <video/display_timing.h>
+
+void display_timings_release(struct display_timings *disp)
+{
+ if (disp->timings) {
+ unsigned int i;
+
+ for (i = 0; i < disp->num_timings; i++)
+ kfree(disp->timings[i]);
+ kfree(disp->timings);
+ }
+ kfree(disp);
+}
+EXPORT_SYMBOL_GPL(display_timings_release);
diff --git a/drivers/video/videomode.c b/drivers/video/videomode.c
new file mode 100644
index 0000000..21c47a2
--- /dev/null
+++ b/drivers/video/videomode.c
@@ -0,0 +1,39 @@
+/*
+ * generic display timing functions
+ *
+ * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar at pengutronix.de>, Pengutronix
+ *
+ * This file is released under the GPLv2
+ */
+
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <video/display_timing.h>
+#include <video/videomode.h>
+
+int videomode_from_timing(const struct display_timings *disp,
+ struct videomode *vm, unsigned int index)
+{
+ struct display_timing *dt;
+
+ dt = display_timings_get(disp, index);
+ if (!dt)
+ return -EINVAL;
+
+ vm->pixelclock = display_timing_get_value(&dt->pixelclock, TE_TYP);
+ vm->hactive = display_timing_get_value(&dt->hactive, TE_TYP);
+ vm->hfront_porch = display_timing_get_value(&dt->hfront_porch, TE_TYP);
+ vm->hback_porch = display_timing_get_value(&dt->hback_porch, TE_TYP);
+ vm->hsync_len = display_timing_get_value(&dt->hsync_len, TE_TYP);
+
+ vm->vactive = display_timing_get_value(&dt->vactive, TE_TYP);
+ vm->vfront_porch = display_timing_get_value(&dt->vfront_porch, TE_TYP);
+ vm->vback_porch = display_timing_get_value(&dt->vback_porch, TE_TYP);
+ vm->vsync_len = display_timing_get_value(&dt->vsync_len, TE_TYP);
+
+ vm->dmt_flags = dt->dmt_flags;
+ vm->data_flags = dt->data_flags;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(videomode_from_timing);
diff --git a/include/video/display_timing.h b/include/video/display_timing.h
new file mode 100644
index 0000000..71e9a38
--- /dev/null
+++ b/include/video/display_timing.h
@@ -0,0 +1,124 @@
+/*
+ * Copyright 2012 Steffen Trumtrar <s.trumtrar at pengutronix.de>
+ *
+ * description of display timings
+ *
+ * This file is released under the GPLv2
+ */
+
+#ifndef __LINUX_DISPLAY_TIMING_H
+#define __LINUX_DISPLAY_TIMING_H
+
+#include <linux/bitops.h>
+#include <linux/types.h>
+
+/* VESA display monitor timing parameters */
+#define VESA_DMT_HSYNC_LOW BIT(0)
+#define VESA_DMT_HSYNC_HIGH BIT(1)
+#define VESA_DMT_VSYNC_LOW BIT(2)
+#define VESA_DMT_VSYNC_HIGH BIT(3)
+
+/* display specific flags */
+#define DISPLAY_FLAGS_DE_LOW BIT(0) /* data enable flag */
+#define DISPLAY_FLAGS_DE_HIGH BIT(1)
+#define DISPLAY_FLAGS_PIXDATA_POSEDGE BIT(2) /* drive data on pos. edge */
+#define DISPLAY_FLAGS_PIXDATA_NEGEDGE BIT(3) /* drive data on neg. edge */
+#define DISPLAY_FLAGS_INTERLACED BIT(4)
+#define DISPLAY_FLAGS_DOUBLESCAN BIT(5)
+
+/*
+ * A single signal can be specified via a range of minimal and maximal values
+ * with a typical value, that lies somewhere inbetween.
+ */
+struct timing_entry {
+ u32 min;
+ u32 typ;
+ u32 max;
+};
+
+enum timing_entry_index {
+ TE_MIN = 0,
+ TE_TYP = 1,
+ TE_MAX = 2,
+};
+
+/*
+ * Single "mode" entry. This describes one set of signal timings a display can
+ * have in one setting. This struct can later be converted to struct videomode
+ * (see include/video/videomode.h). As each timing_entry can be defined as a
+ * range, one struct display_timing may become multiple struct videomodes.
+ *
+ * Example: hsync active high, vsync active low
+ *
+ * Active Video
+ * Video ______________________XXXXXXXXXXXXXXXXXXXXXX_____________________
+ * |<- sync ->|<- back ->|<----- active ----->|<- front ->|<- sync..
+ * | | porch | | porch |
+ *
+ * HSync _|¯¯¯¯¯¯¯¯¯¯|___________________________________________|¯¯¯¯¯¯¯¯¯
+ *
+ * VSync ¯|__________|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯|_________
+ */
+struct display_timing {
+ struct timing_entry pixelclock;
+
+ struct timing_entry hactive; /* hor. active video */
+ struct timing_entry hfront_porch; /* hor. front porch */
+ struct timing_entry hback_porch; /* hor. back porch */
+ struct timing_entry hsync_len; /* hor. sync len */
+
+ struct timing_entry vactive; /* ver. active video */
+ struct timing_entry vfront_porch; /* ver. front porch */
+ struct timing_entry vback_porch; /* ver. back porch */
+ struct timing_entry vsync_len; /* ver. sync len */
+
+ unsigned int dmt_flags; /* VESA DMT flags */
+ unsigned int data_flags; /* video data flags */
+};
+
+/*
+ * This describes all timing settings a display provides.
+ * The native_mode is the default setting for this display.
+ * Drivers that can handle multiple videomodes should work with this struct and
+ * convert each entry to the desired end result.
+ */
+struct display_timings {
+ unsigned int num_timings;
+ unsigned int native_mode;
+
+ struct display_timing **timings;
+};
+
+/* get value specified by index from struct timing_entry */
+static inline u32 display_timing_get_value(const struct timing_entry *te,
+ enum timing_entry_index index)
+{
+ switch (index) {
+ case TE_MIN:
+ return te->min;
+ break;
+ case TE_TYP:
+ return te->typ;
+ break;
+ case TE_MAX:
+ return te->max;
+ break;
+ default:
+ return te->typ;
+ }
+}
+
+/* get one entry from struct display_timings */
+static inline struct display_timing *display_timings_get(const struct
+ display_timings *disp,
+ unsigned int index)
+{
+ if (disp->num_timings > index)
+ return disp->timings[index];
+ else
+ return NULL;
+}
+
+void display_timings_release(struct display_timings *disp);
+
+#endif
diff --git a/include/video/videomode.h b/include/video/videomode.h
new file mode 100644
index 0000000..a421562
--- /dev/null
+++ b/include/video/videomode.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2012 Steffen Trumtrar <s.trumtrar at pengutronix.de>
+ *
+ * generic videomode description
+ *
+ * This file is released under the GPLv2
+ */
+
+#ifndef __LINUX_VIDEOMODE_H
+#define __LINUX_VIDEOMODE_H
+
+#include <linux/types.h>
+#include <video/display_timing.h>
+
+/*
+ * Subsystem independent description of a videomode.
+ * Can be generated from struct display_timing.
+ */
+struct videomode {
+ unsigned long pixelclock; /* pixelclock in Hz */
+
+ u32 hactive;
+ u32 hfront_porch;
+ u32 hback_porch;
+ u32 hsync_len;
+
+ u32 vactive;
+ u32 vfront_porch;
+ u32 vback_porch;
+ u32 vsync_len;
+
+ unsigned int dmt_flags; /* VESA DMT flags */
+ unsigned int data_flags; /* video data flags */
+};
+
+/**
+ * videomode_from_timing - convert display timing to videomode
+ * @disp: structure with all possible timing entries
+ * @vm: return value
+ * @index: index into the list of display timings in devicetree
+ *
+ * DESCRIPTION:
+ * This function converts a struct display_timing to a struct videomode.
+ */
+int videomode_from_timing(const struct display_timings *disp,
+ struct videomode *vm, unsigned int index);
+
+#endif
--
1.7.10.4
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