Re: [RFC PATCH 2/9] powerpc/pseries: fix bad drc_index_start value parsing of drc-info entry

[Tyrel Datwyler <tyreld@linux.ibm.com>]

On 10/10/19 12:04 PM, Nathan Lynch wrote:
> Tyrel Datwyler <tyreld@linux.ibm.com> writes:
>> The ibm,drc-info property is an array property that contains drc-info
>> entries such that each entry is made up of 2 string encoded elements
>> followed by 5 int encoded elements. The of_read_drc_info_cell()
>> helper contains comments that correctly name the expected elements
>> and their encoding. However, the usage of of_prop_next_string() and
>> of_prop_next_u32() introduced a subtle skippage of the first u32.
>> This is a result of of_prop_next_string() returns a pointer to the
>> next property value which is not a string, but actually a (__be32 *).
>> As, a result the following call to of_prop_next_u32() passes over the
>> current int encoded value and actually stores the next one wrongly.
>>
>> Simply endian swap the current value in place after reading the first
>> two string values. The remaining int encoded values can then be read
>> correctly using of_prop_next_u32().
> 
> Good but I think it would make more sense for a fix for
> of_read_drc_info_cell() to precede any patch in the series which
> introduces new callers, such as patch #1.
> 

Not sure it matters that much since everything in the series is required to
properly enable a working drc-info implementation and the call already exists so
it doesn't break bisectability. It ended up second in the series since testing
patch 1 exposed the flaw.

I'll go ahead and move it first, and add the appropriate fixes tag as well which
is currently missing.

-Tyrel