[U-Boot] [PATCH] fdt: fix address cell count checking in fdt_translate_address()

[Stefan Roese <sr@denx.de>]

On 06.11.2015 04:16, Simon Glass wrote:
> Hi,
>
> On 3 November 2015 at 02:57, Przemyslaw Marczak <p.marczak@samsung.com> wrote:
>> Hello All,
>>
>>
>> On 10/29/2015 06:15 PM, Simon Glass wrote:
>>>
>>> Hi Stefan,
>>>
>>> On 28 October 2015 at 08:37, Przemyslaw Marczak <p.marczak@samsung.com>
>>> wrote:
>>>>
>>>> Commit: dm: core: Enable optional use of fdt_translate_address()
>>>>
>>>> Enables use of this function as default, but after this it's not
>>>> possible to get dev address for the case in which: '#size-cells == 0'
>>>>
>>>> This causes errors when getting address for some GPIOs, for which
>>>> the '#size-cells' is set to 0.
>>>>
>>>> Example error:
>>>> '__of_translate_address: Bad cell count for gpx0'
>>>>
>>>> Allowing for that case by modifying the macro 'OF_CHECK_COUNTS',
>>>> (called from )__of_translate_address(), fixes the issue.
>>>>
>>>> Now, this macro doesn't check, that '#size-cells' is greater than 0.
>>>>
>>>> This is possible from the specification point of view, but I'm not sure
>>>> that it doesn't introduce a regression for other configs.
>>>>
>>>> Please test and share the results.
>>>>
>>>> Tested-on: Odroid U3, Odroid X2, Odroid XU3, Sandbox.
>>>>
>>>> Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
>>>> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
>>>> Cc: Lukasz Majewski <l.majewski@samsung.com>
>>>> Cc: Jaehoon Chung <jh80.chung@samsung.com>
>>>> Cc: Stefan Roese <sr@denx.de>
>>>> Cc: Simon Glass <sjg@chromium.org>
>>>> Cc: Bin Meng <bmeng.cn@gmail.com>
>>>> Cc: Marek Vasut <marex@denx.de>
>>>> ---
>>>>    common/fdt_support.c | 7 +++----
>>>>    1 file changed, 3 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/common/fdt_support.c b/common/fdt_support.c
>>>> index f86365e..5f808cc 100644
>>>> --- a/common/fdt_support.c
>>>> +++ b/common/fdt_support.c
>>>> @@ -946,8 +946,7 @@ void fdt_del_node_and_alias(void *blob, const char
>>>> *alias)
>>>>    /* Max address size we deal with */
>>>>    #define OF_MAX_ADDR_CELLS      4
>>>>    #define OF_BAD_ADDR    ((u64)-1)
>>>> -#define OF_CHECK_COUNTS(na, ns)        ((na) > 0 && (na) <=
>>>> OF_MAX_ADDR_CELLS && \
>>>> -                       (ns) > 0)
>>>> +#define OF_CHECK_COUNTS(na)    ((na) > 0 && (na) <= OF_MAX_ADDR_CELLS)
>>>>
>>>>    /* Debug utility */
>>>>    #ifdef DEBUG
>>>> @@ -1115,7 +1114,7 @@ static u64 __of_translate_address(void *blob, int
>>>> node_offset, const fdt32_t *in
>>>>
>>>>           /* Cound address cells & copy address locally */
>>>>           bus->count_cells(blob, parent, &na, &ns);
>>>> -       if (!OF_CHECK_COUNTS(na, ns)) {
>>>> +       if (!OF_CHECK_COUNTS(na)) {
>>>
>>>
>>> This seems to conflict with the comment at the top of this function:
>>>
>>>    * Note: We consider that crossing any level with #size-cells == 0 to
>>> mean
>>>    * that translation is impossible (that is we are not dealing with a
>>> value
>>>    * that can be mapped to a cpu physical address). This is not really
>>> specified
>>>    * that way, but this is traditionally the way IBM at least do things
>>>
>>> What should we do here?
>>>
>>
>> Is that commit acceptable? I would like send V2 with removing the above
>> comment.
>
> That's what I am worried about. Presumably the comment is accurate
> today and this check has some value. I was hoping Stefan might know.

Unfortunately no. I just stumbled over this problem with the
translation of the "complex" ranges on the MVEBU platform. And
noticed that we already have this functionality to translate
the addresses the "right way".

I'm wondering how this problem with those GPIOs is handled in
the kernel? I assume that it is working correctly there, right?
Przemyslaw, could you perhaps check this and see, why its
working there? And change / fix it in U-Boot accordingly?

Thanks,
Stefan