[PATCH v3] mfd: syscon: Decouple syscon interface from platform devices

Hi,

[...]

quoted

please see regmap_get_val_endian called in regmap_init function.
static enum regmap_endian regmap_get_val_endian(struct device *dev,
                                        const struct regmap_bus *bus,
                                        const struct regmap_config

*config) {

quoted

        struct device_node *np = dev->of_node;
        enum regmap_endian endian;
...
}
It will crash at the first line of dev->of_node if dev is NULL.

Can you check if you're using the same code as mine?

No, it's not same.
My bad that I was not using linux-next for testing this patch.
We tested on kgene/for-next where these changes still have not come.
Just now I checked linux-next and found that it will crash at first line of
"regmap_get_val_endian" as there is no check for NULL on dev.

I checked git history of regmap.c file and found recently this file has been
modified
for adding DT endianness binding support. Following are set of patches gone
for this

cf673fb regmap: Split regmap_get_endian() in two functions
5844a8b regmap: Fix handling of volatile registers for format_write() chips
45e1a27 regmap: of_regmap_get_endian() cleanup
ba1b53f regmap: Fix DT endianess parsing logic
d647c19 regmap: add DT endianness binding support.

I think there should have been a check for NULL on "dev" in
"regmap_get_val_endian", so that if dev pointer exist then only it makes
sense to get
endianness property from DT.

I will suggest following fix in regmap.c for this. With following fix I
tested it and it works well
on linux-next also. So if you can confirm following fix is working for you
then I can post this
patch.

--------------------------------------------
Subject: [PATCH] regmap: fix NULL pointer dereference in
 regmap_get_val_endian

Recent commits for getting reg endianess causing NULL pointer
dereference if dev is passed NULL in regmap_init_mmio. This patch
fixes this issue, and allows to parse reg endianess only if dev
and dev->of_node exist.

Another question:

Then the regmap core cannot deal with the following issue:
Like the patch adding the endianness support for syscon:
    [PATCH] mfd: syscon: binding: Add syscon endianness support.

So here just register one dummy syscon device is a good choice I do
think.
:)


Thanks,

BRs
Xiubo