On 3 August 2018 at 16:06, Martin Fuzzey <martin.fuzzey@flowbird.group> wrote: > Hi Emil, > > On 03/08/18 14:35, Emil Velikov wrote: >> >> Hi Martin, >> >> On 1 August 2018 at 15:24, Martin Fuzzey <martin.fuzzey@flowbird.group> >> wrote: >> >> Let's start with the not-so obvious question: >> Why does one open the imx as render node? >> >> Of the top of my head: >> There is nothing in egl/android that should require an authenticated >> device. >> Hence, using a card node should be fine - the etnaviv code opens the >> render node it needs. > > > Yes, the problem is not in egl/android but in the scanout buffer allocation > code. > > etnaviv opens the render node on the *GPU* (for submitting GPU commands), > that part is fine. > > But scanout buffers need to be allocated from imx-drm not etnaviv. > > This done by renderonly_create_kms_dumb_buffer_for_resource() > [src/gallium/auxiliary/renderonly/renderonly.c] > Which uses DRM_IOCTL_MODE_CREATE_DUMB followed by > DRM_IOCTL_PRIME_FD_TO_HANDLE > on the "kms_fd" (probably poorly named because it's not actually used for > modesetting) > see imx_drm_screen_create()[ src/gallium/winsys/imx/drm/imx_drm_winsys.c] > > > If the card node is used DRM_IOCTL_MODE_CREATE_DUMB works but > DRM_IOCTL_PRIME_FD_TO_HANDLE fails, because the permissions are > DRM_AUTH|DRM_UNLOCKED|DRM_RENDER_ALLOW > Right I missed the DRM_AUTH, in the fd <> handle IOCTLs. So in order for things to work, we'd need to either: - allow dumb buffers for render nodes, or - drop the DRM_AUTH for fd <> handle imports Pointing an alternative solution, for kernel developers to analyse and make a decision. > > In android 8.1 the hardware composer runs in a seperate process and it has > to use the card node and be drm master (to use the KMS API), > therefore, when the surface flinger calls > renderonly_create_kms_dumb_buffer_for_resource() it is not authenticated. > > Making surface flinger use a render node fixes the problem for > DRM_IOCTL_PRIME_FD_TO_HANDLE (because that already has DRM_RENDER_ALLOW), > but DRM_IOCTL_MODE_CREATE_DUMB now fails without the patch. > > > This probably worked in previous versions of Android where surface flinger > and hwc were all in the same process. > There has been varying hacks for Android through the years. Bringing details into the discussion will result in a significant diversion. Something we could avoid, for the time being ;-) Thanks Emil _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
