RE: [PATCH v12 2/6] video: add of helper for videomode

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@pengutronix.de Signed-off-by: Philipp Zabel p.zabel@pengutronix.de Acked-by: Stephen Warren swarren@nvidia.com 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

---

.../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@pengutronix.de, Pengutronix
• • based on of_videomode.c by Sascha Hauer s.hauer@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@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@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@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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