Hi Hannes,
(I'm not subscribed to the list, please keep me CC'ed on replies)
On Tuesday 30 May 2017 13:05:00 Hannes Schmelzer wrote:
> With this commit we can modify single values within an array of a dts
> property.
But with this commit U-Boot crashes if you try to create a new property with
the fdt set command :-/
I've tested v2017.07 with the commit reverted, and fdt set works again for me.
The issue is that your fdt_getprop() call fails and return NULL with len set
to -1. You can easily imagine what the memcpy() following it will do.
> This is useful if we have for example a pwm-backlight where we want to
> modifiy the pwm frequency per u-boot script.
>
> The pwm is described in dts like this:
>
> backlight {
> pwms = <0x0000002b 0x00000000 0x004c4b40>;
> };
>
> For changing the frequency, here the 3rd parameter, we simply type:
>
> fdt set /backlight pwms <? ? 0x1E8480>;
>
> For doing all this we:
> - backup the property content into our 'SCRATCHPAD'
> - only modify the array-cell if the new content doesn't start with '?'
>
> Signed-off-by: Hannes Schmelzer <hannes.schmel...@br-automation.com>
>
> ---
>
> cmd/fdt.c | 29 +++++++++++++++++++++--------
> 1 file changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/cmd/fdt.c b/cmd/fdt.c
> index a21415d..e55102a 100644
> --- a/cmd/fdt.c
> +++ b/cmd/fdt.c
> @@ -257,6 +257,7 @@ static int do_fdt(cmd_tbl_t *cmdtp, int flag, int argc,
> char * const argv[])>
> char *prop; /* property */
> int nodeoffset; /* node offset from libfdt */
> static char data[SCRATCHPAD]; /* storage for the property */
> + const void *ptmp;
> int len; /* new length of the property */
> int ret; /* return value */
>
> @@ -268,13 +269,6 @@ static int do_fdt(cmd_tbl_t *cmdtp, int flag, int
> argc, char * const argv[])>
> pathp = argv[2];
> prop = argv[3];
>
> - if (argc == 4) {
> - len = 0;
> - } else {
> - ret = fdt_parse_prop(&argv[4], argc - 4, data, &len);
> - if (ret != 0)
> - return ret;
> - }
>
> nodeoffset = fdt_path_offset (working_fdt, pathp);
> if (nodeoffset < 0) {
> @@ -286,6 +280,21 @@ static int do_fdt(cmd_tbl_t *cmdtp, int flag, int
> argc, char * const argv[])
> return 1;
> }
>
> + if (argc == 4) {
> + len = 0;
> + } else {
> + ptmp = fdt_getprop(working_fdt, nodeoffset, prop,
> &len);
> + if (len > SCRATCHPAD) {
> + printf("prop (%d) doesn't fit in scratchpad!
> \n",
> + len);
> + return 1;
> + }
> + memcpy(data, ptmp, len);
> + ret = fdt_parse_prop(&argv[4], argc - 4, data, &len);
> + if (ret != 0)
> + return ret;
> + }
> +
> ret = fdt_setprop(working_fdt, nodeoffset, prop, data, len);
> if (ret < 0) {
> printf ("libfdt fdt_setprop(): %s\n",
> fdt_strerror(ret));
> @@ -766,7 +775,11 @@ static int fdt_parse_prop(char * const *newval, int
> count, char *data, int *len)
> cp = newp;
> tmp = simple_strtoul(cp, &newp, 0);
>
> - *(fdt32_t *)data = cpu_to_fdt32(tmp);
> + if (*cp != '?')
> + *(fdt32_t *)data = cpu_to_fdt32(tmp);
> + else
> + newp++;
> +
>
> data += 4;
> *len += 4;
--
Regards,
Laurent Pinchart
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