From c8a17756c42581ba1a567d1dd3b69e8f5619a7d8 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Tue, 11 Oct 2022 17:07:08 +0200 Subject: drm/ofdrm: Add ofdrm for Open Firmware framebuffers Open Firmware provides basic display output via the 'display' node. DT platform code already provides a device that represents the node's framebuffer. Add a DRM driver for the device. The display mode and color format is pre-initialized by the system's firmware. Runtime modesetting via DRM is not possible. The display is useful during early boot stages or as error fallback. Similar functionality is already provided by fbdev's offb driver, which is insufficient for modern userspace. The old driver includes support for BootX device tree, which can be found on old 32-bit PowerPC Macintosh systems. If these are still in use, the functionality can be added to ofdrm or implemented in a new driver. As with simpledrm, the fbdev driver cannot be selected if ofdrm is already enabled. Two notable points about the driver: * Reading the framebuffer aperture from the device tree is not reliable on all systems. Ofdrm takes the heuristics and a comment from offb to pick the correct range. * No resource management may be tied to the underlying PCI device. Otherwise the handover to the native driver will fail with a resource conflict. PCI management is therefore done as part of the platform device's cleanup. The driver has been tested on qemu's ppc64le emulation. The device hand-over has been tested with bochs. v5: * use drm_atomic_helper_check_crtc_primary_plane() v4: * set preferred depth to the correct value * set bpp value for console emulation * output scanout-buffer parameters with drm_dbg() v3: * reintegrate FWFB helpers into ofdrm * use damage iterator * sync GEM BOs with drm_gem_fb_{begin,end}_cpu_access() * fix various atomic_check helpers * remove CRTC atomic_{enable,disable} (Javier) * compute stride with drm_format_info_min_pitch() (Daniel) v2: * removed simple-pipe helpers * built driver on top of FWFB helpers * merged all init code into single function * make PCI support optional (Michal) * support COMPILE_TEST (Javier) Signed-off-by: Thomas Zimmermann Reviewed-by: Javier Martinez Canillas convert Link: https://patchwork.freedesktop.org/patch/msgid/20221011150712.3928-2-tzimmermann@suse.de --- MAINTAINERS | 1 + 1 file changed, 1 insertion(+) (limited to 'MAINTAINERS') diff --git a/MAINTAINERS b/MAINTAINERS index 4f2fa9925116..78f670955434 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6653,6 +6653,7 @@ L: dri-devel@lists.freedesktop.org S: Maintained T: git git://anongit.freedesktop.org/drm/drm-misc F: drivers/gpu/drm/drm_aperture.c +F: drivers/gpu/drm/tiny/ofdrm.c F: drivers/gpu/drm/tiny/simpledrm.c F: drivers/video/aperture.c F: include/drm/drm_aperture.h -- cgit v1.2.3