[PATCH v12 2/6] video: add of helper for videomode
Manjunathappa, Prakash
prakash.pm at ti.com
Wed Nov 21 02:12:43 PST 2012
Hi Steffen,
On Tue, Nov 20, 2012 at 21:24:52, Steffen Trumtrar wrote:
> This adds support for reading display timings from DT or/and convert one of those
> timings to a videomode.
> The of_display_timing implementation supports multiple children where each
> property can have up to 3 values. All children are read into an array, that
> can be queried.
> of_get_videomode converts exactly one of that timings to a struct videomode.
>
> Signed-off-by: Steffen Trumtrar <s.trumtrar at pengutronix.de>
> Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
> Acked-by: Stephen Warren <swarren at nvidia.com>
> 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>
> ---
> .../devicetree/bindings/video/display-timings.txt | 107 ++++++++++
> drivers/video/Kconfig | 13 ++
> drivers/video/Makefile | 2 +
> drivers/video/of_display_timing.c | 216 ++++++++++++++++++++
> drivers/video/of_videomode.c | 48 +++++
> include/linux/of_display_timings.h | 20 ++
> include/linux/of_videomode.h | 18 ++
> 7 files changed, 424 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/video/display-timings.txt
> create mode 100644 drivers/video/of_display_timing.c
> create mode 100644 drivers/video/of_videomode.c
> create mode 100644 include/linux/of_display_timings.h
> create mode 100644 include/linux/of_videomode.h
>
> diff --git a/Documentation/devicetree/bindings/video/display-timings.txt b/Documentation/devicetree/bindings/video/display-timings.txt
> new file mode 100644
> index 0000000..a05cade
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/video/display-timings.txt
> @@ -0,0 +1,107 @@
> +display-timings bindings
> +========================
> +
> +display-timings node
> +--------------------
> +
> +required properties:
> + - none
> +
> +optional properties:
> + - native-mode: The native mode for the display, in case multiple modes are
> + provided. When omitted, assume the first node is the native.
> +
> +timings subnode
> +---------------
> +
> +required properties:
> + - hactive, vactive: Display resolution
> + - hfront-porch, hback-porch, hsync-len: Horizontal Display timing parameters
> + in pixels
> + vfront-porch, vback-porch, vsync-len: Vertical display timing parameters in
> + lines
> + - clock-frequency: display clock in Hz
> +
> +optional properties:
> + - hsync-active: Hsync pulse is active low/high/ignored
> + - vsync-active: Vsync pulse is active low/high/ignored
> + - de-active: Data-Enable pulse is active low/high/ignored
> + - pixelclk-inverted: pixelclock is inverted/non-inverted/ignored
> + - interlaced (bool)
> + - doublescan (bool)
> +
> +All the optional properties that are not bool follow the following logic:
> + <1>: high active
> + <0>: low active
> + omitted: not used on hardware
> +
> +There are different ways of describing the capabilities of a display. The devicetree
> +representation corresponds to the one commonly found in datasheets for displays.
> +If a display supports multiple signal timings, the native-mode can be specified.
> +
> +The parameters are defined as
> +
> +struct display_timing
> +=====================
> +
> + +----------+---------------------------------------------+----------+-------+
> + | | ↑ | | |
> + | | |vback_porch | | |
> + | | ↓ | | |
> + +----------###############################################----------+-------+
> + | # ↑ # | |
> + | # | # | |
> + | hback # | # hfront | hsync |
> + | porch # | hactive # porch | len |
> + |<-------->#<---------------+--------------------------->#<-------->|<----->|
> + | # | # | |
> + | # |vactive # | |
> + | # | # | |
> + | # ↓ # | |
> + +----------###############################################----------+-------+
> + | | ↑ | | |
> + | | |vfront_porch | | |
> + | | ↓ | | |
> + +----------+---------------------------------------------+----------+-------+
> + | | ↑ | | |
> + | | |vsync_len | | |
> + | | ↓ | | |
> + +----------+---------------------------------------------+----------+-------+
> +
> +
> +Example:
> +
> + display-timings {
> + native-mode = <&timing0>;
> + timing0: 1920p24 {
> + /* 1920x1080p24 */
> + clock-frequency = <52000000>;
> + hactive = <1920>;
> + vactive = <1080>;
> + hfront-porch = <25>;
> + hback-porch = <25>;
> + hsync-len = <25>;
> + vback-porch = <2>;
> + vfront-porch = <2>;
> + vsync-len = <2>;
> + hsync-active = <1>;
> + };
> + };
> +
> +Every required property also supports the use of ranges, so the commonly used
> +datasheet description with <min typ max>-tuples can be used.
> +
> +Example:
> +
> + timing1: timing {
> + /* 1920x1080p24 */
> + clock-frequency = <148500000>;
> + hactive = <1920>;
> + vactive = <1080>;
> + hsync-len = <0 44 60>;
> + hfront-porch = <80 88 95>;
> + hback-porch = <100 148 160>;
> + vfront-porch = <0 4 6>;
> + vback-porch = <0 36 50>;
> + vsync-len = <0 5 6>;
> + };
> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
> index 2a23b18..807fedd 100644
> --- a/drivers/video/Kconfig
> +++ b/drivers/video/Kconfig
> @@ -39,6 +39,19 @@ config DISPLAY_TIMING
> config VIDEOMODE
> bool
>
> +config OF_DISPLAY_TIMING
> + bool "Enable OF display timing support"
> + select DISPLAY_TIMING
> + help
> + helper to parse display timings from the devicetree
> +
> +config OF_VIDEOMODE
> + bool "Enable OF videomode support"
> + select VIDEOMODE
> + select OF_DISPLAY_TIMING
> + help
> + helper to get videomodes from the devicetree
> +
> menuconfig FB
> tristate "Support for frame buffer devices"
> ---help---
> diff --git a/drivers/video/Makefile b/drivers/video/Makefile
> index fc30439..b936b00 100644
> --- a/drivers/video/Makefile
> +++ b/drivers/video/Makefile
> @@ -168,4 +168,6 @@ 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_OF_DISPLAY_TIMING) += of_display_timing.o
> obj-$(CONFIG_VIDEOMODE) += videomode.o
> +obj-$(CONFIG_OF_VIDEOMODE) += of_videomode.o
> diff --git a/drivers/video/of_display_timing.c b/drivers/video/of_display_timing.c
> new file mode 100644
> index 0000000..3eb731f
> --- /dev/null
> +++ b/drivers/video/of_display_timing.c
> @@ -0,0 +1,216 @@
> +/*
> + * OF helpers for parsing display timings
> + *
> + * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar at pengutronix.de>, Pengutronix
> + *
> + * based on of_videomode.c by Sascha Hauer <s.hauer at pengutronix.de>
> + *
> + * This file is released under the GPLv2
> + */
> +#include <linux/of.h>
> +#include <linux/slab.h>
> +#include <linux/export.h>
> +#include <linux/of_display_timings.h>
> +
> +/**
> + * parse_property - parse timing_entry from device_node
> + * @np: device_node with the property
> + * @name: name of the property
> + * @result: will be set to the return value
> + *
> + * DESCRIPTION:
> + * Every display_timing can be specified with either just the typical value or
> + * a range consisting of min/typ/max. This function helps handling this
> + **/
> +static int parse_property(const struct device_node *np, const char *name,
> + struct timing_entry *result)
> +{
> + struct property *prop;
> + int length, cells, ret;
> +
> + prop = of_find_property(np, name, &length);
> + if (!prop) {
> + pr_err("%s: could not find property %s\n", __func__, name);
> + return -EINVAL;
> + }
> +
> + cells = length / sizeof(u32);
> + if (cells == 1) {
> + ret = of_property_read_u32(np, name, &result->typ);
> + result->min = result->typ;
> + result->max = result->typ;
> + } else if (cells == 3) {
> + ret = of_property_read_u32_array(np, name, &result->min, cells);
> + } else {
> + pr_err("%s: illegal timing specification in %s\n", __func__, name);
> + return -EINVAL;
> + }
> +
> + return ret;
> +}
> +
> +/**
> + * of_get_display_timing - parse display_timing entry from device_node
> + * @np: device_node with the properties
> + **/
> +static struct display_timing *of_get_display_timing(const struct device_node *np)
> +{
> + struct display_timing *dt;
> + int ret = 0;
> +
> + dt = kzalloc(sizeof(*dt), GFP_KERNEL);
> + if (!dt) {
> + pr_err("%s: could not allocate display_timing struct\n", __func__);
> + return NULL;
> + }
> +
> + ret |= parse_property(np, "hback-porch", &dt->hback_porch);
> + ret |= parse_property(np, "hfront-porch", &dt->hfront_porch);
> + ret |= parse_property(np, "hactive", &dt->hactive);
> + ret |= parse_property(np, "hsync-len", &dt->hsync_len);
> + ret |= parse_property(np, "vback-porch", &dt->vback_porch);
> + ret |= parse_property(np, "vfront-porch", &dt->vfront_porch);
> + ret |= parse_property(np, "vactive", &dt->vactive);
> + ret |= parse_property(np, "vsync-len", &dt->vsync_len);
> + ret |= parse_property(np, "clock-frequency", &dt->pixelclock);
> +
> + of_property_read_u32(np, "vsync-active", &dt->vsync_pol_active);
> + of_property_read_u32(np, "hsync-active", &dt->hsync_pol_active);
> + of_property_read_u32(np, "de-active", &dt->de_pol_active);
> + of_property_read_u32(np, "pixelclk-inverted", &dt->pixelclk_pol);
> + dt->interlaced = of_property_read_bool(np, "interlaced");
> + dt->doublescan = of_property_read_bool(np, "doublescan");
> +
> + if (ret) {
> + pr_err("%s: error reading timing properties\n", __func__);
> + kfree(dt);
> + return NULL;
> + }
> +
> + return dt;
> +}
> +
> +/**
> + * of_get_display_timings - parse all display_timing entries from a device_node
> + * @np: device_node with the subnodes
> + **/
> +struct display_timings *of_get_display_timings(const struct device_node *np)
> +{
> + struct device_node *timings_np;
> + struct device_node *entry;
> + struct device_node *native_mode;
> + struct display_timings *disp;
> +
> + if (!np) {
> + pr_err("%s: no devicenode given\n", __func__);
> + return NULL;
> + }
> +
> + timings_np = of_find_node_by_name(np, "display-timings");
I get below build warnings on this line
drivers/video/of_display_timing.c: In function 'of_get_display_timings':
drivers/video/of_display_timing.c:109:2: warning: passing argument 1 of 'of_find_node_by_name' discards qualifiers from pointer target type
include/linux/of.h:167:28: note: expected 'struct device_node *' but argument is of type 'const struct device_node *'
> + if (!timings_np) {
> + pr_err("%s: could not find display-timings node\n", __func__);
> + return NULL;
> + }
> +
> + disp = kzalloc(sizeof(*disp), GFP_KERNEL);
> + if (!disp) {
> + pr_err("%s: could not allocate struct disp'\n", __func__);
> + goto dispfail;
> + }
> +
> + entry = of_parse_phandle(timings_np, "native-mode", 0);
> + /* assume first child as native mode if none provided */
> + if (!entry)
> + entry = of_get_next_child(np, NULL);
> + /* if there is no child, it is useless to go on */
> + if (!entry) {
> + pr_err("%s: no timing specifications given\n", __func__);
> + goto entryfail;
> + }
> +
> + pr_info("%s: using %s as default timing\n", __func__, entry->name);
> +
> + native_mode = entry;
> +
> + disp->num_timings = of_get_child_count(timings_np);
> + if (disp->num_timings == 0) {
> + /* should never happen, as entry was already found above */
> + pr_err("%s: no timings specified\n", __func__);
> + goto entryfail;
> + }
> +
> + disp->timings = kzalloc(sizeof(struct display_timing *) * disp->num_timings,
> + GFP_KERNEL);
> + if (!disp->timings) {
> + pr_err("%s: could not allocate timings array\n", __func__);
> + goto entryfail;
> + }
> +
> + disp->num_timings = 0;
> + disp->native_mode = 0;
> +
> + for_each_child_of_node(timings_np, entry) {
> + struct display_timing *dt;
> +
> + dt = of_get_display_timing(entry);
> + if (!dt) {
> + /*
> + * to not encourage wrong devicetrees, fail in case of
> + * an error
> + */
> + pr_err("%s: error in timing %d\n", __func__,
> + disp->num_timings + 1);
> + goto timingfail;
> + }
> +
> + if (native_mode == entry)
> + disp->native_mode = disp->num_timings;
> +
> + disp->timings[disp->num_timings] = dt;
> + disp->num_timings++;
> + }
> + of_node_put(timings_np);
> + of_node_put(native_mode);
> +
> + if (disp->num_timings > 0)
> + pr_info("%s: got %d timings. Using timing #%d as default\n",
> + __func__, disp->num_timings, disp->native_mode + 1);
> + else {
> + pr_err("%s: no valid timings specified\n", __func__);
> + display_timings_release(disp);
> + return NULL;
> + }
> + return disp;
> +
> +timingfail:
> + if (native_mode)
> + of_node_put(native_mode);
> + display_timings_release(disp);
> +entryfail:
> + if (disp)
> + kfree(disp);
> +dispfail:
> + of_node_put(timings_np);
> + return NULL;
> +}
> +EXPORT_SYMBOL_GPL(of_get_display_timings);
> +
> +/**
> + * of_display_timings_exists - check if a display-timings node is provided
> + * @np: device_node with the timing
> + **/
> +int of_display_timings_exists(const struct device_node *np)
> +{
> + struct device_node *timings_np;
> +
> + if (!np)
> + return -EINVAL;
> +
> + timings_np = of_parse_phandle(np, "display-timings", 0);
Also here:
drivers/video/of_display_timing.c: In function 'of_display_timings_exists':
drivers/video/of_display_timing.c:209:2: warning: passing argument 1 of 'of_parse_phandle' discards qualifiers from pointer target type
include/linux/of.h:258:28: note: expected 'struct device_node *' but argument is of type 'const struct device_node *'
Thanks,
Prakash
> + if (!timings_np)
> + return -EINVAL;
> +
> + of_node_put(timings_np);
> + return 1;
> +}
> +EXPORT_SYMBOL_GPL(of_display_timings_exists);
> diff --git a/drivers/video/of_videomode.c b/drivers/video/of_videomode.c
> new file mode 100644
> index 0000000..c573f92
> --- /dev/null
> +++ b/drivers/video/of_videomode.c
> @@ -0,0 +1,48 @@
> +/*
> + * generic videomode helper
> + *
> + * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar at pengutronix.de>, Pengutronix
> + *
> + * This file is released under the GPLv2
> + */
> +#include <linux/of.h>
> +#include <linux/of_display_timings.h>
> +#include <linux/of_videomode.h>
> +#include <linux/export.h>
> +
> +/**
> + * of_get_videomode - get the videomode #<index> from devicetree
> + * @np - devicenode with the display_timings
> + * @vm - set to return value
> + * @index - index into list of display_timings
> + * DESCRIPTION:
> + * Get a list of all display timings and put the one
> + * specified by index into *vm. This function should only be used, if
> + * only one videomode is to be retrieved. A driver that needs to work
> + * with multiple/all videomodes should work with
> + * of_get_display_timings instead.
> + **/
> +int of_get_videomode(const struct device_node *np, struct videomode *vm,
> + int index)
> +{
> + struct display_timings *disp;
> + int ret;
> +
> + disp = of_get_display_timings(np);
> + if (!disp) {
> + pr_err("%s: no timings specified\n", __func__);
> + return -EINVAL;
> + }
> +
> + if (index == OF_USE_NATIVE_MODE)
> + index = disp->native_mode;
> +
> + ret = videomode_from_timing(disp, vm, index);
> + if (ret)
> + return ret;
> +
> + display_timings_release(disp);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(of_get_videomode);
> diff --git a/include/linux/of_display_timings.h b/include/linux/of_display_timings.h
> new file mode 100644
> index 0000000..2b4fa0a
> --- /dev/null
> +++ b/include/linux/of_display_timings.h
> @@ -0,0 +1,20 @@
> +/*
> + * Copyright 2012 Steffen Trumtrar <s.trumtrar at pengutronix.de>
> + *
> + * display timings of helpers
> + *
> + * This file is released under the GPLv2
> + */
> +
> +#ifndef __LINUX_OF_DISPLAY_TIMINGS_H
> +#define __LINUX_OF_DISPLAY_TIMINGS_H
> +
> +#include <linux/display_timing.h>
> +#include <linux/of.h>
> +
> +#define OF_USE_NATIVE_MODE -1
> +
> +struct display_timings *of_get_display_timings(const struct device_node *np);
> +int of_display_timings_exists(const struct device_node *np);
> +
> +#endif
> diff --git a/include/linux/of_videomode.h b/include/linux/of_videomode.h
> new file mode 100644
> index 0000000..4de5fcc
> --- /dev/null
> +++ b/include/linux/of_videomode.h
> @@ -0,0 +1,18 @@
> +/*
> + * Copyright 2012 Steffen Trumtrar <s.trumtrar at pengutronix.de>
> + *
> + * videomode of-helpers
> + *
> + * This file is released under the GPLv2
> + */
> +
> +#ifndef __LINUX_OF_VIDEOMODE_H
> +#define __LINUX_OF_VIDEOMODE_H
> +
> +#include <linux/videomode.h>
> +#include <linux/of.h>
> +
> +int of_get_videomode(const struct device_node *np, struct videomode *vm,
> + int index);
> +
> +#endif /* __LINUX_OF_VIDEOMODE_H */
> --
> 1.7.10.4
>
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