[PATCHv14 3/7] video: add of helper for display timings/videomode
Leela Krishna Amudala
l.krishna at samsung.com
Fri Nov 23 02:19:37 PST 2012
Hello Steffen,
On Fri, Nov 23, 2012 at 2:34 PM, Steffen Trumtrar
<s.trumtrar at pengutronix.de> wrote:
> This adds support for reading display timings from DT into a struct
> display_timings. The of_display_timing implementation supports multiple
> subnodes. All children are read into an array, that can be queried.
>
> If no native mode is specified, the first subnode will be used.
>
> For cases, where the graphics drivers knows, there can be only one
> mode description or where the driver only supports one mode, a helper
> function of_get_videomode is added, that gets a struct videomode from DT.
> (As this function is implemented in an expensive fashion, it should only
> be used in the aforementioned case).
>
> This also demonstrates how of_display_timings may be utilized.
>
> 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>
> Acked-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
> .../devicetree/bindings/video/display-timings.txt | 107 ++++++++++
> drivers/video/Kconfig | 15 ++
> drivers/video/Makefile | 2 +
> drivers/video/of_display_timing.c | 223 ++++++++++++++++++++
> drivers/video/of_videomode.c | 48 +++++
> include/linux/of_display_timings.h | 20 ++
> include/linux/of_videomode.h | 18 ++
> 7 files changed, 433 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
>
<<<snip>>>
> diff --git a/drivers/video/of_display_timing.c b/drivers/video/of_display_timing.c
> new file mode 100644
> index 0000000..645f43d
> --- /dev/null
> +++ b/drivers/video/of_display_timing.c
> @@ -0,0 +1,223 @@
> +/*
> + * 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(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");
> + 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);
> + /*
> + * native_mode points to the device_node returned by of_parse_phandle
> + * therefore call of_node_put on it
> + */
> + 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);
I'm seeing warning for the above call
"passing argument 1 of 'of_parse_phandle' discards qualifiers from
pointer target type
expected 'struct device_node *' but argument is of type 'const struct
device_node *' "
Please take care of it.
Best Wishes,
Leela Krishna Amudala
> + 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..358aa56
> --- /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(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..b3e3455
> --- /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(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..a72ad78
> --- /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(struct device_node *np, struct videomode *vm,
> + int index);
> +
> +#endif /* __LINUX_OF_VIDEOMODE_H */
> --
> 1.7.10.4
>
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