[U-Boot] [PATCH 3/5] fdt: add fdt_add_display_timings(..)

[Stefano Babic]

Hi Christian,

On 08/01/2014 08:24, Christian Gmeiner wrote:
> This new function is used to set all display-timings
> properties based on fb_videomode.
> 
> display-timings {
> 	timing0 {
> 		clock-frequency = <25000000>;
> 		hactive = <640>;
> 		vactive = <480>;
> 		hback-porch = <48>;
> 		hfront-porch = <16>;
> 		vback-porch = <31>;
> 		vfront-porch = <12>;
> 		hsync-len = <96>;
> 		vsync-len = <2>;
> 	};
> };
> 
> Signed-off-by: Christian Gmeiner <christian.gmeiner at gmail.com>
> ---
>  common/fdt_support.c  |   23 +++++++++++++++++++++++
>  include/fdt_support.h |    3 +++
>  2 files changed, 26 insertions(+)
> 
> diff --git a/common/fdt_support.c b/common/fdt_support.c
> index 4e32b02..cf81a4b 100644
> --- a/common/fdt_support.c
> +++ b/common/fdt_support.c
> @@ -11,6 +11,7 @@
>  #include <stdio_dev.h>
>  #include <linux/ctype.h>
>  #include <linux/types.h>
> +#include <linux/fb.h>
>  #include <asm/global_data.h>
>  #include <libfdt.h>
>  #include <fdt_support.h>
> @@ -1342,6 +1343,28 @@ err_size:
>  #endif
>  
>  /*
> + * fdt_add_display_timings: add display-timings properties
> + *
> + * @fdt: ptr to device tree
> + * @noff: node to update
> + * @mode: ptr to b_videomode
> + */
> +void fdt_add_display_timings(void *fdt, int noff, struct fb_videomode *mode)
> +{
> +	if (noff != -FDT_ERR_NOTFOUND) {
> +		fdt_setprop_u32(fdt, noff, "clock-frequency", mode->pixclock);
> +		fdt_setprop_u32(fdt, noff, "hactive", mode->xres);
> +		fdt_setprop_u32(fdt, noff, "vactive", mode->yres);
> +		fdt_setprop_u32(fdt, noff, "hback-porch", mode->left_margin);
> +		fdt_setprop_u32(fdt, noff, "hfront-porch", mode->right_margin);
> +		fdt_setprop_u32(fdt, noff, "vback-porch", mode->upper_margin);
> +		fdt_setprop_u32(fdt, noff, "vfront-porch", mode->lower_margin);
> +		fdt_setprop_u32(fdt, noff, "hsync-len", mode->hsync_len);
> +		fdt_setprop_u32(fdt, noff, "vsync-len", mode->vsync_len);
> +	}
> +}
> +
> +/*
>   * Verify the physical address of device tree node for a given alias
>   *
>   * This function locates the device tree node of a given alias, and then
> diff --git a/include/fdt_support.h b/include/fdt_support.h
> index 9871e2f..1c54880 100644
> --- a/include/fdt_support.h
> +++ b/include/fdt_support.h
> @@ -82,6 +82,9 @@ int fdt_set_phandle(void *fdt, int nodeoffset, uint32_t phandle);
>  unsigned int fdt_create_phandle(void *fdt, int nodeoffset);
>  int fdt_add_edid(void *blob, const char *compat, unsigned char *buf);
>  
> +struct fb_videomode;
> +void fdt_add_display_timings(void *blob, int noff, struct fb_videomode *mode);
> +
>  int fdt_verify_alias_address(void *fdt, int anode, const char *alias,
>  			      u64 addr);
>  u64 fdt_get_base_address(void *fdt, int node);
> 

Agree that we have to sync u-boot and kernel, and this can be a way in
the short term.

I am asking if this is in the long term the best way to do it. You are
converting EDID values to fb_videomode *mode, and then again to the
device node as required by DT.
We have already had some talks about moving U-Boot configuration to DT,
that is U-Boot can be also configured by a DT file (see for example
support for Nvidia processors, they already support DT in U-Boot).

Anatolji, what do you think as best solution we have to follow for
display setting ?

Best regards,
Stefano Babic

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