+ Abhinav From: Srinivas Pullakavi (QUIC) Sent: Monday, January 22, 2024 10:44 PM To: 'Yiwei Zhang' <zzyi...@chromium.org> Cc: Rob Clark <robdcl...@gmail.com>; mesa-dev@lists.freedesktop.org Subject: RE: GBM as standalone buffer allocator
Hi Yiwei, Looks like this thread is closed. https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26038#note_2243187 Can we collaborate on this? Thanks, Srinivas From: Yiwei Zhang <zzyi...@chromium.org<mailto:zzyi...@chromium.org>> Sent: Monday, November 20, 2023 4:38 AM To: Srinivas Pullakavi (QUIC) <quic_spull...@quicinc.com<mailto:quic_spull...@quicinc.com>> Cc: Rob Clark <robdcl...@gmail.com<mailto:robdcl...@gmail.com>>; mesa-dev@lists.freedesktop.org<mailto:mesa-dev@lists.freedesktop.org> Subject: Re: GBM as standalone buffer allocator There’s https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26038. It is quite appealing to me considering a VK only scenario. On Thu, Nov 2, 2023 at 5:50 AM Srinivas Pullakavi (QUIC) <quic_spull...@quicinc.com<mailto:quic_spull...@quicinc.com>> wrote: Hi Rob, Thanks for your inputs. We are planning to use DMA-Buf for GBM backend. DMA-buf supported heaps are listed in /dev/dma_heap/ Gbm backend selects the best heap based on usage. For example: Secure buffers will be allocated from secure heap. Sample output: # ls /dev/dma_heap reserved system Sample code to allocate a buffer from system heap: int heap_fd = open(/dev/dma_heap/system, O_RDONLY | O_CLOEXEC)) struct dma_heap_allocation_data heap_data { .len = size, // length of data to be allocated in bytes .fd_flags = O_RDWR | O_CLOEXEC, // permissions for the memory to be allocated }; int status = ioctl(heap_fd, DMA_HEAP_IOCTL_ALLOC, &heap_data) if (status == 0) { int buffer_fd = heap_data.fd; } In this case, there is no dependency on display / Graphics driver. But still GBM create device expects a device fd to be passed. Can we make it optional to pass device fd ? Thanks, Srinivas -----Original Message----- From: Rob Clark <robdcl...@gmail.com<mailto:robdcl...@gmail.com>> Sent: Tuesday, October 24, 2023 1:06 AM To: Srinivas Pullakavi (QUIC) <quic_spull...@quicinc.com<mailto:quic_spull...@quicinc.com>> Cc: mesa-dev@lists.freedesktop.org<mailto:mesa-dev@lists.freedesktop.org> Subject: Re: GBM as standalone buffer allocator On Mon, Oct 23, 2023 at 6:22 AM Srinivas Pullakavi (QUIC) <quic_spull...@quicinc.com<mailto:quic_spull...@quicinc.com>> wrote: > > Hi, > > > > We are planning to enhance GBM as a standalone buffer allocator, which > can be used for all multi-media clients. Ex: video, camera, display > etc; > > > > GBM create device expects a file descriptor to be passed, which points to drm > node. This brings in a dependency on display for buffer allocation. On > headless devices where display driver is not present, GBM cannot be used for > buffer allocations. E.g. Recording cases where pipeline is setup between > Camera, Video, Graphics. > Note that you need some sort of device to allocate buffers from. With mesa and upstream kernel, that would be the drm device. (However as Adam points out, a drm device does not necessarily need a display.. for example, several vendors have compute-only GPUs (pci) which have no display outputs.) You might want to look at ChromeOS's minigbm. It already handles these cases (buffer sharing across display/gpu/video/camera). BR, -R [1] https://chromium.googlesource.com/chromiumos/platform/minigbm/ > > Could you please share your comments on what will be a good design to make > GBM flexible for above? > > > > Thanks, > > Srinivas > >
