On Tue, Jun 16, 2020 at 01:59:51PM +0200, Drew Fustini wrote:
> On Tue, Jun 16, 2020 at 10:31:54AM +0200, Linus Walleij wrote:
> > On Mon, Jun 8, 2020 at 2:51 PM Drew Fustini <drew@xxxxxxxxxxxxxxx> wrote:
> >
> > > This patch causes pcs_parse_pinconf() to return -ENOTSUPP when no
> > > pinctrl_map is added. The current behavior is to return 0 when
> > > !PCS_HAS_PINCONF or !nconfs. Thus pcs_parse_one_pinctrl_entry()
> > > incorrectly assumes that a map was added and sets num_maps = 2.
> > >
> > > Analysis:
> > > =========
> > > The function pcs_parse_one_pinctrl_entry() calls pcs_parse_pinconf()
> > > if PCS_HAS_PINCONF is enabled. The function pcs_parse_pinconf()
> > > returns 0 to indicate there was no error and num_maps is then set to 2:
> > >
> > > 980 static int pcs_parse_one_pinctrl_entry(struct pcs_device *pcs,
> > > 981 struct device_node *np,
> > > 982 struct pinctrl_map **map,
> > > 983 unsigned *num_maps,
> > > 984 const char **pgnames)
> > > 985 {
> > > <snip>
> > > 1053 (*map)->type = PIN_MAP_TYPE_MUX_GROUP;
> > > 1054 (*map)->data.mux.group = np->name;
> > > 1055 (*map)->data.mux.function = np->name;
> > > 1056
> > > 1057 if (PCS_HAS_PINCONF && function) {
> > > 1058 res = pcs_parse_pinconf(pcs, np, function, map);
> > > 1059 if (res)
> > > 1060 goto free_pingroups;
> > > 1061 *num_maps = 2;
> > > 1062 } else {
> > > 1063 *num_maps = 1;
> > > 1064 }
> > >
> > > However, pcs_parse_pinconf() will also return 0 if !PCS_HAS_PINCONF or
> > > !nconfs. I believe these conditions should indicate that no map was
> > > added by returning -ENOTSUPP. Otherwise pcs_parse_one_pinctrl_entry()
> > > will set num_maps = 2 even though no maps were successfully added, as
> > > it does not reach "m++" on line 940:
> > >
> > > 895 static int pcs_parse_pinconf(struct pcs_device *pcs, struct device_node *np,
> > > 896 struct pcs_function *func,
> > > 897 struct pinctrl_map **map)
> > > 898
> > > 899 {
> > > 900 struct pinctrl_map *m = *map;
> > > <snip>
> > > 917 /* If pinconf isn't supported, don't parse properties in below. */
> > > 918 if (!PCS_HAS_PINCONF)
> > > 919 return 0;
> > > 920
> > > 921 /* cacluate how much properties are supported in current node */
> > > 922 for (i = 0; i < ARRAY_SIZE(prop2); i++) {
> > > 923 if (of_find_property(np, prop2[i].name, NULL))
> > > 924 nconfs++;
> > > 925 }
> > > 926 for (i = 0; i < ARRAY_SIZE(prop4); i++) {
> > > 927 if (of_find_property(np, prop4[i].name, NULL))
> > > 928 nconfs++;
> > > 929 }
> > > 930 if (!nconfs)
> > > 919 return 0;
> > > 932
> > > 933 func->conf = devm_kcalloc(pcs->dev,
> > > 934 nconfs, sizeof(struct pcs_conf_vals),
> > > 935 GFP_KERNEL);
> > > 936 if (!func->conf)
> > > 937 return -ENOMEM;
> > > 938 func->nconfs = nconfs;
> > > 939 conf = &(func->conf[0]);
> > > 940 m++;
> > >
> > > This situtation will cause a boot failure [0] on the BeagleBone Black
> > > (AM3358) when am33xx_pinmux node in arch/arm/boot/dts/am33xx-l4.dtsi
> > > has compatible = "pinconf-single" instead of "pinctrl-single".
> > >
> > > The patch fixes this issue by returning -ENOSUPP when !PCS_HAS_PINCONF
> > > or !nconfs, so that pcs_parse_one_pinctrl_entry() will know that no
> > > map was added.
> > >
> > > Logic is also added to pcs_parse_one_pinctrl_entry() to distinguish
> > > between -ENOSUPP and other errors. In the case of -ENOSUPP, num_maps
> > > is set to 1 as it is valid for pinconf to be enabled and a given pin
> > > group to not any pinconf properties.
> > >
> > > [0] https://lore.kernel.org/linux-omap/20200529175544.GA3766151@x1/
> > >
> > > Fixes: 9dddb4df90d1 ("pinctrl: single: support generic pinconf")
> > > Signed-off-by: Drew Fustini <drew@xxxxxxxxxxxxxxx>
> >
> > Patch applied as non-critical (for-next) fix.
> >
> > If there is no hurry let's merge it this way with lots of testing
> > along the way.
> >
> > Yours,
> > Linus Walleij
>
> Thanks, I agree more testing is a good idea.
>
> In particular, do you have a way to followup with Haojian Zhuang within
> Linaro?
>
Linus - do you have a way to contact Haojian Zhuan?
I found them on Freenode but they have been idle since beginning of
June. Last email I can find on the mailing list is from March.
Tony and I would both like someone familiar with Hisilicon to comment on
this patch as it is using pinctrl-single.
Thanks,
Drew
