Hi,
On Mon, Oct 08, 2012 at 10:07:45AM +0300, Tomi Valkeinen wrote:
> Hi,
>
> On Thu, 2012-10-04 at 19:59 +0200, Steffen Trumtrar wrote:
> > Signed-off-by: Steffen Trumtrar <s.trumtrar@xxxxxxxxxxxxxx>
> > ---
> > .../devicetree/bindings/video/display-timings.txt | 222 ++++++++++++++++++++
> > drivers/of/Kconfig | 5 +
> > drivers/of/Makefile | 1 +
> > drivers/of/of_display_timings.c | 183 ++++++++++++++++
> > include/linux/of_display_timings.h | 85 ++++++++
> > 5 files changed, 496 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/video/display-timings.txt
> > create mode 100644 drivers/of/of_display_timings.c
> > create mode 100644 include/linux/of_display_timings.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..45e39bd
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/video/display-timings.txt
> > @@ -0,0 +1,222 @@
> > +display-timings bindings
> > +==================
> > +
> > +display-timings-node
> > +------------
> > +
> > +required properties:
> > + - none
> > +
> > +optional properties:
> > + - default-timing: the default timing value
> > +
> > +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: displayclock in Hz
> > +
> > +optional properties:
> > + - hsync-active-high (bool): Hsync pulse is active high
> > + - vsync-active-high (bool): Vsync pulse is active high
> > + - de-active-high (bool): Data-Enable pulse is active high
> > + - pixelclk-inverted (bool): pixelclock is inverted
> > + - interlaced (bool)
> > + - doublescan (bool)
>
> I think bool should be generally used for things that are on/off, like
> interlace. For hsync-active-high & others I'd rather have 0/1 values as
> others already suggested.
>
> > +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 default-timing can be specified.
> > +
> > +The parameters are defined as
> > +
> > +struct signal_timing
> > +===================
> > +
> > + +----------+---------------------------------------------+----------+-------+
> > + | | ↑ | | |
> > + | | |vback_porch | | |
> > + | | ↓ | | |
> > + +----------###############################################----------+-------+
> > + | # ↑ # | |
> > + | # | # | |
> > + | hback # | # hfront | hsync |
> > + | porch # | hactive # porch | len |
> > + |<-------->#<---------------+--------------------------->#<-------->|<----->|
> > + | # | # | |
> > + | # |vactive # | |
> > + | # | # | |
> > + | # ↓ # | |
> > + +----------###############################################----------+-------+
> > + | | ↑ | | |
> > + | | |vfront_porch | | |
> > + | | ↓ | | |
> > + +----------+---------------------------------------------+----------+-------+
> > + | | ↑ | | |
> > + | | |vsync_len | | |
> > + | | ↓ | | |
> > + +----------+---------------------------------------------+----------+-------+
> > +
> > +
> > +Example:
> > +
> > + display-timings {
> > + default-timing = <&timing0>;
> > + timing0: 1920p24 {
> > + /* 1920x1080p24 */
>
> I think this is commonly called 1080p24.
>
Oops. Yes, you are right.
> > + clock = <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-high;
> > + };
> > + };
> > +
> > +Every 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 = <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>;
> > + };
> > +
> > +Usage in backend
> > +================
> > +
> > +A backend driver may choose to use the display-timings directly and convert the timing
> > +ranges to a suitable mode. Or it may just use the conversion of the display timings
> > +to the required mode via the generic videomode struct.
> > +
> > + dtb
> > + |
> > + | of_get_display_timing_list
> > + ↓
> > + struct display_timings
> > + |
> > + | videomode_from_timing
> > + ↓
> > + --- struct videomode ---
> > + | |
> > + videomode_to_displaymode | | videomode_to_fb_videomode
> > + ↓ ↓
> > + drm_display_mode fb_videomode
> > +
> > +The functions of_get_fb_videomode and of_get_display_mode are provided
> > +to conveniently get the respective mode representation from the devicetree.
> > +
> > +Conversion to videomode
> > +=======================
> > +
> > +As device drivers normally work with some kind of video mode, the timings can be
> > +converted (may be just a simple copying of the typical value) to a generic videomode
> > +structure which then can be converted to the according mode used by the backend.
> > +
> > +Supported modes
> > +===============
> > +
> > +The generic videomode read in by the driver can be converted to the following
> > +modes with the following parameters
> > +
> > +struct fb_videomode
> > +===================
> > +
> > + +----------+---------------------------------------------+----------+-------+
> > + | | ↑ | | |
> > + | | |upper_margin | | |
> > + | | ↓ | | |
> > + +----------###############################################----------+-------+
> > + | # ↑ # | |
> > + | # | # | |
> > + | # | # | |
> > + | # | # | |
> > + | left # | # right | hsync |
> > + | margin # | xres # margin | len |
> > + |<-------->#<---------------+--------------------------->#<-------->|<----->|
> > + | # | # | |
> > + | # | # | |
> > + | # | # | |
> > + | # |yres # | |
> > + | # | # | |
> > + | # | # | |
> > + | # | # | |
> > + | # | # | |
> > + | # | # | |
> > + | # | # | |
> > + | # | # | |
> > + | # | # | |
> > + | # ↓ # | |
> > + +----------###############################################----------+-------+
> > + | | ↑ | | |
> > + | | |lower_margin | | |
> > + | | ↓ | | |
> > + +----------+---------------------------------------------+----------+-------+
> > + | | ↑ | | |
> > + | | |vsync_len | | |
> > + | | ↓ | | |
> > + +----------+---------------------------------------------+----------+-------+
> > +
> > +clock in nanoseconds
> > +
> > +struct drm_display_mode
> > +=======================
> > +
> > + +----------+---------------------------------------------+----------+-------+
> > + | | | | | ↑
> > + | | | | | |
> > + | | | | | |
> > + +----------###############################################----------+-------+ |
> > + | # ↑ ↑ ↑ # | | |
> > + | # | | | # | | |
> > + | # | | | # | | |
> > + | # | | | # | | |
> > + | # | | | # | | |
> > + | # | | | hdisplay # | | |
> > + | #<--+--------------------+-------------------># | | |
> > + | # | | | # | | |
> > + | # |vsync_start | # | | |
> > + | # | | | # | | |
> > + | # | |vsync_end | # | | |
> > + | # | | |vdisplay # | | |
> > + | # | | | # | | |
> > + | # | | | # | | |
> > + | # | | | # | | | vtotal
> > + | # | | | # | | |
> > + | # | | | hsync_start # | | |
> > + | #<--+---------+----------+------------------------------>| | |
> > + | # | | | # | | |
> > + | # | | | hsync_end # | | |
> > + | #<--+---------+----------+-------------------------------------->| |
> > + | # | | ↓ # | | |
> > + +----------####|#########|################################----------+-------+ |
> > + | | | | | | | |
> > + | | | | | | | |
> > + | | ↓ | | | | |
> > + +----------+-------------+-------------------------------+----------+-------+ |
> > + | | | | | | |
> > + | | | | | | |
> > + | | ↓ | | | ↓
> > + +----------+---------------------------------------------+----------+-------+
> > + htotal
> > + <------------------------------------------------------------------------->
> > +
> > +clock in kilohertz
> > diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
> > index dfba3e6..646deb0 100644
> > --- a/drivers/of/Kconfig
> > +++ b/drivers/of/Kconfig
> > @@ -83,4 +83,9 @@ config OF_MTD
> > depends on MTD
> > def_bool y
> >
> > +config OF_DISPLAY_TIMINGS
> > + def_bool y
> > + help
> > + helper to parse display timings from the devicetree
> > +
> > endmenu # OF
> > diff --git a/drivers/of/Makefile b/drivers/of/Makefile
> > index e027f44..c8e9603 100644
> > --- a/drivers/of/Makefile
> > +++ b/drivers/of/Makefile
> > @@ -11,3 +11,4 @@ obj-$(CONFIG_OF_MDIO) += of_mdio.o
> > obj-$(CONFIG_OF_PCI) += of_pci.o
> > obj-$(CONFIG_OF_PCI_IRQ) += of_pci_irq.o
> > obj-$(CONFIG_OF_MTD) += of_mtd.o
> > +obj-$(CONFIG_OF_DISPLAY_TIMINGS) += of_display_timings.o
> > diff --git a/drivers/of/of_display_timings.c b/drivers/of/of_display_timings.c
> > new file mode 100644
> > index 0000000..e47bc63
> > --- /dev/null
> > +++ b/drivers/of/of_display_timings.c
> > @@ -0,0 +1,183 @@
> > +/*
> > + * OF helpers for parsing display timings
> > + *
> > + * Copyright (c) 2012 Steffen Trumtrar <s.trumtrar@xxxxxxxxxxxxxx>, Pengutronix
> > + *
> > + * based on of_videomode.c by Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> > + *
> > + * 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>
> > +
> > +/* every signal_timing can be specified with either
> > + * just the typical value or a range consisting of
> > + * min/typ/max.
> > + * This function helps handling this
> > + */
>
> The comment is not according to kernel coding style. And I'd start the
> sentence with a capital letter =).
>
> > +static int parse_property(struct device_node *np, char *name,
> > + struct timing_entry *result)
> > +{
> > + struct property *prop;
> > + int length;
> > + int cells;
> > + int 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_array(np, name, &result->typ, cells);
> > + 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;
> > +}
> > +
> > +struct signal_timing *of_get_display_timing(struct device_node *np)
> > +{
> > + struct signal_timing *st;
> > + int ret = 0;
> > +
> > + st = kzalloc(sizeof(*st), GFP_KERNEL);
> > +
> > + if (!st) {
> > + pr_err("%s: could not allocate signal_timing struct\n", __func__);
> > + return NULL;
> > + }
> > +
> > + ret |= parse_property(np, "hback-porch", &st->hback_porch);
> > + ret |= parse_property(np, "hfront-porch", &st->hfront_porch);
> > + ret |= parse_property(np, "hactive", &st->hactive);
> > + ret |= parse_property(np, "hsync-len", &st->hsync_len);
> > + ret |= parse_property(np, "vback-porch", &st->vback_porch);
> > + ret |= parse_property(np, "vfront-porch", &st->vfront_porch);
> > + ret |= parse_property(np, "vactive", &st->vactive);
> > + ret |= parse_property(np, "vsync-len", &st->vsync_len);
> > + ret |= parse_property(np, "clock", &st->pixelclock);
> > +
> > + st->vsync_pol_active_high = of_property_read_bool(np, "vsync-active-high");
> > + st->hsync_pol_active_high = of_property_read_bool(np, "hsync-active-high");
> > + st->de_pol_active_high = of_property_read_bool(np, "de-active-high");
> > + st->pixelclk_pol_inverted = of_property_read_bool(np, "pixelclk-inverted");
> > + st->interlaced = of_property_read_bool(np, "interlaced");
> > + st->doublescan = of_property_read_bool(np, "doublescan");
> > +
> > + if (ret) {
> > + pr_err("%s: error reading timing properties\n", __func__);
> > + return NULL;
> > + }
> > +
> > + return st;
> > +}
> > +EXPORT_SYMBOL_GPL(of_get_display_timing);
> > +
> > +struct display_timings *of_get_display_timing_list(struct device_node *np)
> > +{
> > + struct device_node *timings_np;
> > + struct device_node *entry;
> > + struct display_timings *disp;
> > + char *default_timing;
> > +
> > + 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);
> > +
> > + entry = of_parse_phandle(timings_np, "default-timing", 0);
> > +
> > + if (!entry) {
> > + pr_info("%s: no default-timing specified\n", __func__);
> > + entry = of_find_node_by_name(np, "timing");
> > + }
>
> If "default-timing" property is optional, I don't see any need for the
> pr_info above, as it should be business as usual if the property doesn't
> exist.
>
> If the default-timing property doesn't exist, wouldn't it be simpler to
> get the first subnode, instead of looking one with "timing" name?
>
Yes. I will fix that.
> > +
> > + if (!entry) {
> > + pr_info("%s: no timing specifications given\n", __func__);
> > + return disp;
> > + }
>
> Again, I don't think the pr_info is needed if this is a normal case.
> Then again, perhaps this could be an error? Why would there be a display
> node without any timings?
>
This should be an error. It is a relict from trying to define the display instead
of just the timings. I need to rework the whole no/wrong timings thing.
> > +
> > + pr_info("%s: using %s as default timing\n", __func__, entry->name);
> > +
> > + default_timing = (char *)entry->full_name;
>
> const char *?
>
> > +
> > + disp->num_timings = 0;
> > +
> > + for_each_child_of_node(timings_np, entry) {
> > + disp->num_timings++;
> > + }
>
> No need for { }
>
Okay.
> > + disp->timings = kzalloc(sizeof(struct signal_timing *)*disp->num_timings,
> > + GFP_KERNEL);
> > +
> > + disp->num_timings = 0;
> > +
> > + for_each_child_of_node(timings_np, entry) {
> > + struct signal_timing *st;
> > +
> > + st = of_get_display_timing(entry);
> > +
> > + if (!st)
> > + continue;
> > +
> > + if (strcmp(default_timing, entry->full_name) == 0)
> > + disp->default_timing = disp->num_timings;
>
> I don't see you setting disp->default_timing to OF_DEFAULT_TIMING in
> case there's no default_timing found.
>
> Or, at least I presume OF_DEFAULT_TIMING is meant to mark non-existing
> default timing. The name OF_DEFAULT_TIMING is not very descriptive to
> me.
>
> Would it make more sense to have the disp->default_timing as a pointer
> to the timing, instead of index? Then a NULL value would mark a
> non-existing default timing.
>
> > + disp->timings[disp->num_timings] = st;
> > + disp->num_timings++;
> > + }
> > +
> > +
> > + of_node_put(timings_np);
> > +
> > + if (disp->num_timings >= 0)
> > + pr_info("%s: got %d timings. Using timing #%d as default\n", __func__,
> > + disp->num_timings , disp->default_timing + 1);
> > + else
> > + pr_info("%s: no timings specified\n", __func__);
> > +
> > + return disp;
> > +}
> > +EXPORT_SYMBOL_GPL(of_get_display_timing_list);
> > +
> > +int of_display_timings_exists(struct device_node *np)
> > +{
> > + struct device_node *timings_np;
> > + struct device_node *default_np;
> > +
> > + if (!np)
> > + return -EINVAL;
> > +
> > + timings_np = of_parse_phandle(np, "display-timings", 0);
> > +
> > + if (!timings_np)
> > + return -EINVAL;
> > +
> > + default_np = of_parse_phandle(np, "default-timing", 0);
> > +
> > + if (default_np)
> > + return 0;
> > +
> > + return -EINVAL;
> > +}
> > +EXPORT_SYMBOL_GPL(of_display_timings_exists);
> > diff --git a/include/linux/of_display_timings.h b/include/linux/of_display_timings.h
> > new file mode 100644
> > index 0000000..1ad719e
> > --- /dev/null
> > +++ b/include/linux/of_display_timings.h
> > @@ -0,0 +1,85 @@
> > +/*
> > + * Copyright 2012 Steffen Trumtrar <s.trumtrar@xxxxxxxxxxxxxx>
> > + *
> > + * description of display timings
> > + *
> > + * This file is released under the GPLv2
> > + */
> > +
> > +#ifndef __LINUX_OF_DISPLAY_TIMINGS_H
> > +#define __LINUX_OF_DISPLAY_TIMINGS_H
> > +
> > +#define OF_DEFAULT_TIMING -1
> > +
> > +struct display_timings {
> > + unsigned int num_timings;
> > + unsigned int default_timing;
> > +
> > + struct signal_timing **timings;
>
> Should this be a pointer to a const array of const data? Is there ever
> need to change them after they've been read from DT?
>
No, there isn't. Will change to const.
> > +};
> > +
> > +struct timing_entry {
> > + u32 min;
> > + u32 typ;
> > + u32 max;
> > +};
> > +
> > +struct signal_timing {
> > + struct timing_entry pixelclock;
> > +
> > + struct timing_entry hactive;
> > + struct timing_entry hfront_porch;
> > + struct timing_entry hback_porch;
> > + struct timing_entry hsync_len;
> > +
> > + struct timing_entry vactive;
> > + struct timing_entry vfront_porch;
> > + struct timing_entry vback_porch;
> > + struct timing_entry vsync_len;
> > +
> > + bool vsync_pol_active_high;
> > + bool hsync_pol_active_high;
> > + bool de_pol_active_high;
> > + bool pixelclk_pol_inverted;
> > + bool interlaced;
> > + bool doublescan;
> > +};
> > +
> > +struct display_timings *of_get_display_timing_list(struct device_node *np);
> > +struct signal_timing *of_get_display_timing(struct device_node *np);
> > +int of_display_timings_exists(struct device_node *np);
> > +
> > +/* placeholder function until ranges are really needed */
> > +static inline u32 signal_timing_get_value(struct timing_entry *te, int index)
> > +{
> > + return te->typ;
> > +}
> > +
> > +static inline void timings_release(struct display_timings *disp)
> > +{
> > + int i;
> > +
> > + for (i = 0; i < disp->num_timings; i++)
> > + kfree(disp->timings[i]);
> > +}
> > +
> > +static inline void display_timings_release(struct display_timings *disp)
> > +{
> > + timings_release(disp);
> > + kfree(disp->timings);
> > +}
> > +
> > +static inline struct signal_timing *display_timings_get(struct display_timings *disp,
> > + int index)
> > +{
> > + struct signal_timing *st;
> > +
> > + if (disp->num_timings > index) {
> > + st = disp->timings[index];
> > + return st;
> > + }
> > + else
> > + return NULL;
> > +}
>
> Why do you have these functions in the header file?
>
Well, ... there actually isn't any reason any longer. I will move them.
Thanks and regards,
Steffen
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
http://lists.freedesktop.org/mailman/listinfo/dri-devel
