[U-Boot] why does fdt_fixup_ethernet() need to worry about an edited FDT?
Bin Meng
bmeng.cn at gmail.com
Wed May 25 04:23:49 CEST 2016
On Tue, May 24, 2016 at 8:55 PM, Robert P. J. Day <rpjday at crashcourse.ca> wrote:
>
> looking at the code for fdt_fixup_ethernet() in fdt_support.c, and
> i'm puzzled by the extra work being done ostensibly to take an
> "edited" FDT into account:
>
> void fdt_fixup_ethernet(void *fdt)
> {
> int i, j, prop;
> char *tmp, *end;
> char mac[16];
> const char *path;
> unsigned char mac_addr[6];
> int offset;
>
> if (fdt_path_offset(fdt, "/aliases") < 0)
> return;
>
> /* Cycle through all aliases */
> for (prop = 0; ; prop++) {
> const char *name;
> int len = strlen("ethernet");
>
> /* FDT might have been edited, recompute the offset */
> offset = fdt_first_property_offset(fdt,
> fdt_path_offset(fdt, "/aliases"));
> /* Select property number 'prop' */
> for (i = 0; i < prop; i++)
> offset = fdt_next_property_offset(fdt, offset);
> ... snip ...
>
> why is it that *this* routine has to worry about an edited FDT, but
> nothing else i see in that entire source file has to? as a (hopefully)
> relevant example:
>
> #if defined(OF_STDOUT_PATH)
> static int fdt_fixup_stdout(void *fdt, int chosenoff)
> {
> return fdt_setprop(fdt, chosenoff, "linux,stdout-path",
> OF_STDOUT_PATH, strlen(OF_STDOUT_PATH) + 1);
> }
>
> that routine simply calls fdt_setprop() ... what is it about
> fdt_fixup_ethernet() that needs to take extra care compared to every
> other function in that file?
>
Commit a434fd1d282fd32d81296c6d4c2e0911f6e488b3 explains this.
Regards,
Bin
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