Hi all
2014/1/14 Christian Gmeiner christian.gmeiner@gmail.com:
2014/1/12 Anatolij Gustschin agust@denx.de:
Hi Stefano,
On Wed, 08 Jan 2014 11:53:39 +0100 Stefano Babic sbabic@denx.de wrote: ...
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 ?
many drivers use struct fb_videomode internally and this display-timings binding already exists in linux, so I think a function for converting from fb_videomode to DT is useful. However we should probably extend this current implementation of the function, e.g. rename it to fdt_update_display_timings() and pass more arguments: node compatible and the name of the parent node containing the display-timings node. The code for searching the display-timings node is also needed for other boards, so if it is in the function itself, it will simplify the usage.
This function could look for display-timings node and create it if it doesn't exist. Or update the existing node with new info.
Thanks for your comments... will come up with something in the next version of the patch series.
I have some time to work on this patch.
Anatolij are you happy witht the following functions?
int fdt_find_display_timings(void *fdt, const char *compat, const char *parent) { int coff = fdt_node_offset_by_compatible(fdt, -1, compat); int poff = fdt_subnode_offset(fdt, coff, parent); int timings = fdt_subnode_offset(fdt, poff, "display-timings");
return timings; }
int fdt_update_display_timings(void *fdt, const char *compat, const char *parent, struct fb_videomode *mode) { int timings = fdt_find_display_timings(fdt, compat, parent);
/* check if display-timings subnode does exist */ if (timings == -FDT_ERR_NOTFOUND) { return timings; }
/* set all needed properties */ if (timings != -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); }
return 0; }
This would allow us to update an existing display-timings node via
fdt_update_display_timings(blob, "fsl,imx6q-ldb", "lvds-channel", mode);
Note: not even compile tested :)
thanks -- Christian Gmeiner, MSc