From 222ec45f4c69dfa8cd02c72928147ac06dffffa2 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Tue, 3 Nov 2020 10:30:15 +0100 Subject: drm/fb_helper: Support framebuffers in I/O memory At least sparc64 requires I/O-specific access to framebuffers. This patch updates the fbdev console accordingly. For drivers with direct access to the framebuffer memory, the callback functions in struct fb_ops test for the type of memory and call the rsp fb_sys_ of fb_cfb_ functions. Read and write operations are implemented internally by DRM's fbdev helper. For drivers that employ a shadow buffer, fbdev's blit function retrieves the framebuffer address as struct dma_buf_map, and uses dma_buf_map interfaces to access the buffer. The bochs driver on sparc64 uses a workaround to flag the framebuffer as I/O memory and avoid a HW exception. With the introduction of struct dma_buf_map, this is not required any longer. The patch removes the rsp code from both, bochs and fbdev. v7: * use min_t(size_t,) (kernel test robot) * return the number of bytes read/written, if any (fbdev testcase) v5: * implement fb_read/fb_write internally (Daniel, Sam) v4: * move dma_buf_map changes into separate patch (Daniel) * TODO list: comment on fbdev updates (Daniel) Signed-off-by: Thomas Zimmermann Reviewed-by: Daniel Vetter Reviewed-by: Sam Ravnborg Tested-by: Sam Ravnborg Link: https://patchwork.freedesktop.org/patch/msgid/20201103093015.1063-11-tzimmermann@suse.de --- Documentation/gpu/todo.rst | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) (limited to 'Documentation/gpu') diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index 59f63f1d7680..acca232b025b 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -201,13 +201,28 @@ Convert drivers to use drm_fbdev_generic_setup() ------------------------------------------------ Most drivers can use drm_fbdev_generic_setup(). Driver have to implement -atomic modesetting and GEM vmap support. Current generic fbdev emulation -expects the framebuffer in system memory (or system-like memory). +atomic modesetting and GEM vmap support. Historically, generic fbdev emulation +expected the framebuffer in system memory or system-like memory. By employing +struct dma_buf_map, drivers with frambuffers in I/O memory can be supported +as well. Contact: Maintainer of the driver you plan to convert Level: Intermediate +Reimplement functions in drm_fbdev_fb_ops without fbdev +------------------------------------------------------- + +A number of callback functions in drm_fbdev_fb_ops could benefit from +being rewritten without dependencies on the fbdev module. Some of the +helpers could further benefit from using struct dma_buf_map instead of +raw pointers. + +Contact: Thomas Zimmermann , Daniel Vetter + +Level: Advanced + + drm_framebuffer_funcs and drm_mode_config_funcs.fb_create cleanup ----------------------------------------------------------------- -- cgit v1.2.3