Re: [PATCH 1/1] powerpc: fix fdt_fixup_liodn_tbl_fman()

[Marek Behún]

On Wed, 12 Oct 2022 19:13:11 +0200
Heinrich Schuchardt <heinrich.schucha...@canonical.com> wrote:

> Builiding with GCC 12.2 fails:
> 
>     arch/powerpc/cpu/mpc85xx/liodn.c: In function 'fdt_fixup_liodn_tbl_fman':
>     arch/powerpc/cpu/mpc85xx/liodn.c:340:35: error: the comparison will
>     always evaluate as 'false' for the address of 'compat'
>     will never be NULL [-Werror=address]
>       340 |                 if (tbl[i].compat == NULL)
>           |
> 
> Remove the superfluous check.
> 
> Fixes: 97a8d010e029 ("net/fman: Support both new and legacy FMan Compatibles")
> Signed-off-by: Heinrich Schuchardt <heinrich.schucha...@canonical.com>
> ---
>  arch/powerpc/cpu/mpc85xx/liodn.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/arch/powerpc/cpu/mpc85xx/liodn.c 
> b/arch/powerpc/cpu/mpc85xx/liodn.c
> index a084002494..2d55916841 100644
> --- a/arch/powerpc/cpu/mpc85xx/liodn.c
> +++ b/arch/powerpc/cpu/mpc85xx/liodn.c
> @@ -337,9 +337,6 @@ static void fdt_fixup_liodn_tbl_fman(void *blob,
>       for (i = 0; i < sz; i++) {
>               int off;
>  
> -             if (tbl[i].compat == NULL)
> -                     continue;
> -
>               /* Try the new compatible first.
>                * If the node is missing, try the old.
>                */

This is the wrong fix, IMO. Instead we should do something like

diff --git a/arch/powerpc/cpu/mpc85xx/liodn.c b/arch/powerpc/cpu/mpc85xx/liodn.c
index a084002494..41b7d53ec3 100644
--- a/arch/powerpc/cpu/mpc85xx/liodn.c
+++ b/arch/powerpc/cpu/mpc85xx/liodn.c
@@ -337,7 +337,7 @@ static void fdt_fixup_liodn_tbl_fman(void *blob,
        for (i = 0; i < sz; i++) {
                int off;
 
-               if (tbl[i].compat == NULL)
+               if (tbl[i].compat[0] == NULL)
                        continue;
 
                /* Try the new compatible first.
@@ -345,7 +345,7 @@ static void fdt_fixup_liodn_tbl_fman(void *blob,
                  */
                off = fdt_node_offset_by_compat_reg(blob,
                                tbl[i].compat[0], tbl[i].compat_offset);
-               if (off < 0)
+               if (off < 0 && tbl[i].compat[1] != NULL)
                        off = fdt_node_offset_by_compat_reg(blob,
                                        tbl[i].compat[1], tbl[i].compat_offset);