[Mesa-stable] [Mesa-dev] [PATCH v2 2/2] mesa: _mesa_format_convert should be endian agnostic

[Oded Gabbay]

On Fri, Aug 7, 2015 at 10:37 PM, Oded Gabbay <oded.gabbay at gmail.com> wrote:
> On Fri, Aug 7, 2015 at 10:30 PM, Matt Turner <mattst88 at gmail.com> wrote:
>> On Fri, Aug 7, 2015 at 12:24 PM, Oded Gabbay <oded.gabbay at gmail.com> wrote:
>>> This patch fixes a bug that is manifested in the read path of mesa when
>>> running on big-endian machines. The effects can be seen when running
>>> piglit sanity test and/or taking a screen capture.
>>>
>>> The bug is caused when _mesa_format_convert receives src_format as
>>> mesa_format, which it thens changes to mesa_array_format. During this
>>> change, it checks for endianness and swaps the bytes accordingly.
>>> However, because the bytes are _already_ swapped in the memory itself
>>> (being written there by llvmpipe/softpipe/sw rast), and src_format
>>> value matches the _actual_ contents of the memory, the result of the
>>> read is wrong.
>>>
>>> Therefore, because other layers/functions, such as llvm or
>>> read_rgba_pixels() takes care whether we are dealing with big-endian or
>>> little-endian, _mesa_format_convert should be endian agnostic to avoid
>>> duplicate swapping of bytes.
>>>
>>> btw, it is also mentioned in the comment of the function that it doesn't
>>> handle byte-swapping, so the original code contradicts the documentation.
>>>
>>> Signed-off-by: Oded Gabbay <oded.gabbay at gmail.com>
>>> CC: "10.5 10.6" <mesa-stable at lists.freedesktop.org>
>>> Signed-off-by: Oded Gabbay <oded.gabbay at gmail.com>
>>
>> Multiple S-o-b. Whoops. Just fix before committing. :)
> Matt, thanks for catching that :)
> Oded

Matt,
Just wanted to ask if your comment was also an r-b for this patch ?

    Oded