[Mesa-dev] [PATCH 4/4] gbm: Add map/unmap functions

[Daniel Stone]

Hi,

On 23 April 2016 at 03:08, Rob Herring <robh at kernel.org> wrote:
> On Fri, Apr 22, 2016 at 6:32 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>> Can we take a look at the GBM gralloc as well. One thing that worries
>> me is that (most likely) you are requesting/creating a bo without
>> GBM_BO_USE_WRITE whist using MAP + CPU write UNMAP. If you do set the
>> USE_WRITE flag, you're getting a dumb buffer, which I'm not sure how
>> well is going to work.
>
> I'm not using GBM_BO_USE_WRITE and that is not a condition for mapping
> given that flag is tied to cursors (according to comments) and gives
> dumb buffers. Also of note, if gralloc flags are set for r/w often,
> then I request a linear buffer. Here's the gralloc side:

Right, I wouldn't take GBM_BO_USE_WRITE to have much of an effect on
mappings, as it pessimises allocation like you say.

Cheers,
Daniel