Re: [RESEND PATCH v2 v4.1-rc8 0/2] drm: prime: Allow exported dma-bufs to be mapped

From: Daniel Vetter
Date: Fri Jun 19 2015 - 11:45:35 EST

On Fri, Jun 19, 2015 at 02:52:27PM +0100, Daniel Thompson wrote:
> This patch set started out as a single patch with a trivial bit of
> boilerplate to add dmabuf mmap support to the msm driver. However Rob
> Clark pointed out that, rather than keep one of the tricks I had used, it
> would be better to change the helpers resulting in this series.
> I've tested this both with a rather hacked about Android userspace
> and with a fairly small test case run from debian. Both bits of code
> currently use dumb buffers.
> Thanks to Benjamin Gaignard for his help in finding this bit of code and
> to Damien Hobson-Garcia for pointing out that I'd forgotten (since 3.18)
> to RESEND these patches.
> Dave: I guess its probably too late in the dev. cycle to take this code
> but don't worry, I will try really hard to remember to RESEND it
> for 4.2. ;-)
> v2:
> * Modified DRM_PRIME_HANDLE_TO_FD to honour the O_RDRW from the user
> and removed code to workaround this from the sti driver (Rob Clark).
> * Added a patch to (rather spartanly) document gem_prime_mmap. Only
> tacked into this series 'cos I spotted it was missing when I was
> checking whether I needed to describe DRM_RDRW anywhere.

Oh hornets nest since I just screamed around again against drm prime mmap
support ;-) Imo before we expose this for real we really need to somehow
figure out what to do about cache coherency. Some intel folks are looking
into adding suitable ioctls to the dma-buf fd to make this possible. I
think we should wait with enabling drm prime mmaping before that's
resolved somehow. I'll point them at your patches though to make sure they
don't reinvent this wheel here.

> Daniel Thompson (2):
> drm: prime: Honour O_RDWR during prime-handle-to-fd
> drm: prime: Document gem_prime_mmap
> drivers/gpu/drm/drm_prime.c | 13 ++++++-------
> include/uapi/drm/drm.h | 1 +
> 2 files changed, 7 insertions(+), 7 deletions(-)
> --
> 2.4.3
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Daniel Vetter
Software Engineer, Intel Corporation
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