Hi,
[add Daniel Vetter] [cc dri-devel]
Den 29.05.2019 15.09, skrev Pierre Yves MORDRET:
Hello Noralf,
Sorry for bothering you with question but I need to better understand the rational about a patch you did in DRM/GEM.
First of all, let me introduce myself. I'm currently employee to STMicroelectronics company and in charge of GPU integration within STM32 MPU (Cortex A7 + Cortex M4)
On Cortex A7 is running a Linux Kernel 4.19 as for today.
We came across some trouble when we switch from Kernel 4.14 to 4.19 for GPU stack. On august you submit this commit :
90378e58919285637aa0f063c04ba0c6449d98b1 drm/gem: drm_gem_dumb_map_offset(): reject dma-buf
Reject mapping an imported dma-buf since is's an invalid use-case.In Userland GPU stack we have such statements : bo_map_fd DRM_IOCTL_MODE_MAP_DUMB mmap (offset)
With the patch above, ioctl returns an error EINVAL and prevents the nmap. As for today we revert this patch and it works fine in our end.
Thus the questions are :
- what is the rational behind this fix ?
- What we doing wrong this situation ?
- What do we need in such situation ?
I need to pass those on to Daniel Vetter (DRM maintainer) since he wanted the change. The details were never clear to me. Some of the discussion is here: https://patchwork.freedesktop.org/patch/172242/
Noralf.
Many thanks in advance. Best Regards