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

[Simon Glass]

Hi Przemyslaw,

On 8 January 2016 at 05:01, Przemyslaw Marczak <p.marczak at samsung.com> wrote:
> Hello Simon,
>
>
> On 01/07/2016 08:24 PM, Simon Glass wrote:
>>
>> +Stephen
>>
>> On 4 January 2016 at 17:59, Simon Glass <sjg at chromium.org> wrote:
>>>
>>> Hi Przemyslaw,
>>>
>>> On 5 November 2015 at 23:47, Stefan Roese <sr at denx.de> wrote:
>>>>
>>>> On 06.11.2015 04:16, Simon Glass wrote:
>>>>>
>>>>>
>>>>> Hi,
>>>>>
>>>>> On 3 November 2015 at 02:57, Przemyslaw Marczak <p.marczak at 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 at 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 at samsung.com>
>>>>>>>> Cc: Masahiro Yamada <yamada.masahiro at socionext.com>
>>>>>>>> Cc: Lukasz Majewski <l.majewski at samsung.com>
>>>>>>>> Cc: Jaehoon Chung <jh80.chung at samsung.com>
>>>>>>>> Cc: Stefan Roese <sr at denx.de>
>>>>>>>> Cc: Simon Glass <sjg at chromium.org>
>>>>>>>> Cc: Bin Meng <bmeng.cn at gmail.com>
>>>>>>>> Cc: Marek Vasut <marex at 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?
>>>
>>>
>>> Let's pick up this patch for now as a bug-fix. We can deal with this
>>> problem after the release.
>>
>>
>> Applied to u-boot-dm/master.
>>
>> I'll post a revert after the release. It seems like you and Stephen
>> are making good progress.
>>
>> - Simon
>>
>>
>
> Why so fast with this one?
>
> I think, that more proper for a temporary fix is my latest patch with
> #size-cells count checking only if ranges found in the parent node.
>
> I will continue the discussion with Stephen.

The release is scheduled for today, so we had to do something to fix
the breakage.

Once you have a full solution figured out we can revert this patch and
apply what you come up with.

Regards,
Simon