[RFC v4 22/25] drm/fb-helper: Add generic fbdev emulation
Daniel Vetter
daniel at ffwll.ch
Mon Apr 16 08:52:25 UTC 2018
On Sat, Apr 14, 2018 at 01:53:15PM +0200, Noralf Trønnes wrote:
> This adds generic fbdev emulation for drivers that supports
> dumb buffers which they can export.
>
> All the driver has to do is call drm_fbdev_generic_setup().
>
> Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
> ---
> drivers/gpu/drm/drm_fb_helper.c | 255 ++++++++++++++++++++++++++++++++++++++++
> include/drm/drm_fb_helper.h | 20 ++++
> 2 files changed, 275 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index b1124c08b1ed..1954de5b13e0 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -30,6 +30,7 @@
> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>
> #include <linux/console.h>
> +#include <linux/dma-buf.h>
> #include <linux/kernel.h>
> #include <linux/sysrq.h>
> #include <linux/slab.h>
> @@ -1995,6 +1996,260 @@ void drm_fb_helper_output_poll_changed(struct drm_device *dev)
> }
> EXPORT_SYMBOL(drm_fb_helper_output_poll_changed);
>
> +static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
> +{
> + struct drm_fb_helper *fb_helper = info->par;
> +
> + return dma_buf_mmap(fb_helper->buffer->dma_buf, vma, 0);
> +}
> +
> +/*
> + * fb_ops.fb_destroy is called by the last put_fb_info() call at the end of
> + * unregister_framebuffer() or fb_release().
> + */
> +static void drm_fbdev_fb_destroy(struct fb_info *info)
> +{
> + struct drm_fb_helper *fb_helper = info->par;
> + struct fb_ops *fbops = NULL;
> +
> + DRM_DEBUG("\n");
> +
> + if (fb_helper->fbdev->fbdefio)
> + fbops = fb_helper->fbdev->fbops;
> +
> + drm_fb_helper_fini(fb_helper);
> + drm_client_framebuffer_delete(fb_helper->buffer);
> + drm_client_free(fb_helper->client);
> + kfree(fb_helper);
> + kfree(fbops);
> +}
> +
> +static struct fb_ops drm_fbdev_fb_ops = {
> + /*
> + * No need to set owner, this module is already pinned by the driver.
> + * A reference is taken on the driver module in drm_fb_helper_fb_open()
> + * to prevent the driver going away with open fd's.
> + */
> + DRM_FB_HELPER_DEFAULT_OPS,
> + .fb_open = drm_fb_helper_fb_open,
> + .fb_release = drm_fb_helper_fb_release,
> + .fb_destroy = drm_fbdev_fb_destroy,
> + .fb_mmap = drm_fbdev_fb_mmap,
> + .fb_read = drm_fb_helper_sys_read,
> + .fb_write = drm_fb_helper_sys_write,
> + .fb_fillrect = drm_fb_helper_sys_fillrect,
> + .fb_copyarea = drm_fb_helper_sys_copyarea,
> + .fb_imageblit = drm_fb_helper_sys_imageblit,
> +};
> +
> +static struct fb_deferred_io drm_fbdev_defio = {
> + .delay = HZ / 20,
> + .deferred_io = drm_fb_helper_deferred_io,
> +};
> +
> +/* Hack to test tinydrm before converting to vmalloc buffers */
> +static int drm_fbdev_cma_deferred_io_mmap(struct fb_info *info,
> + struct vm_area_struct *vma)
> +{
> + fb_deferred_io_mmap(info, vma);
> + vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
> +
> + return 0;
> +}
> +
> +static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
> + struct drm_fb_helper_surface_size *sizes)
> +{
> + struct drm_client_dev *client = fb_helper->client;
> + struct drm_display_mode sizes_mode = {
> + .hdisplay = sizes->surface_width,
> + .vdisplay = sizes->surface_height,
> + };
> + struct drm_client_buffer *buffer;
> + struct drm_framebuffer *fb;
> + struct fb_info *fbi;
> + u32 format;
> + int ret;
> +
> + DRM_DEBUG_KMS("surface width(%d), height(%d) and bpp(%d)\n",
> + sizes->surface_width, sizes->surface_height,
> + sizes->surface_bpp);
> +
> + format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
> + buffer = drm_client_framebuffer_create(client, &sizes_mode, format);
> + if (IS_ERR(buffer))
> + return PTR_ERR(buffer);
> +
> + fb_helper->buffer = buffer;
> + fb_helper->fb = buffer->fb;
> + fb = buffer->fb;
> +
> + fbi = drm_fb_helper_alloc_fbi(fb_helper);
> + if (IS_ERR(fbi)) {
> + ret = PTR_ERR(fbi);
> + goto err_free_buffer;
> + }
> +
> + fbi->par = fb_helper;
> + fbi->fbops = &drm_fbdev_fb_ops;
> + fbi->screen_size = fb->height * fb->pitches[0];
> + fbi->fix.smem_len = fbi->screen_size;
> + fbi->screen_buffer = buffer->vaddr;
> + strcpy(fbi->fix.id, "DRM emulated");
> +
> + drm_fb_helper_fill_fix(fbi, fb->pitches[0], fb->format->depth);
> + drm_fb_helper_fill_var(fbi, fb_helper, sizes->fb_width, sizes->fb_height);
> +
> + /*
> + * Drivers that set the dirty callback:
> + * - Doesn't use defio:
> + * i915, virtio, rockchip
> + * - defio with vmalloc buffer blitted on the real one:
> + * vmwgfx
> + * - defio is disabled because it doesn't work with shmem:
> + * udl
> + * - defio with special dirty callback for fbdev, uses vmalloc for fbdev:
> + * qxl
> + * - defio with cma buffer, will move to vmalloc buffers:
> + * tinydrm
> + *
> + * TODO:
> + * Maybe add vmalloc shadow buffer support.
> + */
> +
> + if (fb->funcs->dirty) {
> + struct fb_ops *fbops;
> +
> + /*
> + * fb_deferred_io_cleanup() clears &fbops->fb_mmap so a per
> + * instance version is necessary.
> + */
> + fbops = kzalloc(sizeof(*fbops), GFP_KERNEL);
> + if (!fbops) {
> + ret = -ENOMEM;
> + goto err_fb_info_destroy;
> + }
> +
> + *fbops = *fbi->fbops;
> + fbi->fbops = fbops;
> +
> + fbi->fbdefio = &drm_fbdev_defio;
> +
> + /* Hack so I can test with tinydrm */
> + fbi->fix.smem_start = page_to_phys(virt_to_page(buffer->vaddr));
> +
> + fb_deferred_io_init(fbi);
> +
> + /* Hack so I can test with tinydrm */
> + fbi->fbops->fb_mmap = drm_fbdev_cma_deferred_io_mmap;
> + }
> +
> + return 0;
> +
> +err_fb_info_destroy:
> + drm_fb_helper_fini(fb_helper);
> +err_free_buffer:
> + drm_client_framebuffer_delete(buffer);
> +
> + return ret;
> +}
I'd split this patch into 2:
- First one just adds the generic_probe callback. We could then start
rolling that one out to lots of drivers, which would give all this code
lots of testing.
- Second part is the generic client stuff below. Again then with follow-up
patches to roll it out.
This way we could achieve a slightly more gradual transition of drivers.
And the first step should only be replacing the fb_probe callback.
-Daniel
> +
> +static const struct drm_fb_helper_funcs drm_fb_helper_generic_funcs = {
> + .fb_probe = drm_fb_helper_generic_probe,
> +};
> +
> +static int drm_fbdev_client_remove(struct drm_client_dev *client)
> +{
> + struct drm_fb_helper *fb_helper = client->private;
> +
> + if (!fb_helper->fbdev) {
> + kfree(fb_helper);
> + return 0;
> + }
> +
> + unregister_framebuffer(fb_helper->fbdev);
> +
> + /*
> + * If userspace is closed the client is now freed by
> + * drm_fbdev_fb_destroy(), otherwise it will be freed on the last close.
> + * Return 1 to tell that freeing is taken care of.
> + */
> +
> + return 1;
> +}
> +
> +static int drm_fbdev_client_lastclose(struct drm_client_dev *client)
> +{
> + struct drm_fb_helper *fb_helper = client->private;
> +
> + drm_fb_helper_restore_fbdev_mode_unlocked(fb_helper);
> +
> + return 0;
> +}
> +
> +static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
> +{
> + struct drm_fb_helper *fb_helper = client->private;
> +
> + if (fb_helper->fbdev)
> + return 0;
> +
> + return drm_fb_helper_fbdev_setup(client->dev, fb_helper,
> + &drm_fb_helper_generic_funcs,
> + fb_helper->preferred_bpp, 0);
> +}
> +
> +static const struct drm_client_funcs drm_fbdev_client_funcs = {
> + .name = "fbdev",
> + .remove = drm_fbdev_client_remove,
> + .lastclose = drm_fbdev_client_lastclose,
> + .hotplug = drm_fbdev_client_hotplug,
> +};
> +
> +/**
> + * drm_fb_helper_generic_fbdev_setup() - Setup generic fbdev emulation
> + * @dev: DRM device
> + * @preferred_bpp: Preferred bits per pixel for the device.
> + * @dev->mode_config.preferred_depth is used if this is zero.
> + *
> + * This function sets up generic fbdev emulation for drivers that supports
> + * dumb buffers which can be exported.
> + *
> + * Restore, hotplug events and teardown are all taken care of. Drivers that does
> + * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
> + * Simple drivers might use drm_mode_config_helper_suspend().
> + *
> + * Returns:
> + * Zero on success or negative error code on failure.
> + */
> +int drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
> +{
> + struct drm_fb_helper *fb_helper;
> + struct drm_client_dev *client;
> +
> + if (!drm_fbdev_emulation)
> + return 0;
> +
> + fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
> + if (!fb_helper)
> + return -ENOMEM;
> +
> + client = drm_client_new(dev, &drm_fbdev_client_funcs);
> + if (IS_ERR(client)) {
> + kfree(fb_helper);
> + return PTR_ERR(client);
> + }
> +
> + client->private = fb_helper;
> + fb_helper->client = client;
> + fb_helper->preferred_bpp = preferred_bpp;
> +
> + drm_fbdev_client_hotplug(client);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_fbdev_generic_setup);
> +
> /* The Kconfig DRM_KMS_HELPER selects FRAMEBUFFER_CONSOLE (if !EXPERT)
> * but the module doesn't depend on any fb console symbols. At least
> * attempt to load fbcon to avoid leaving the system without a usable console.
> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> index 330983975d5e..711da1747836 100644
> --- a/include/drm/drm_fb_helper.h
> +++ b/include/drm/drm_fb_helper.h
> @@ -126,6 +126,20 @@ struct drm_fb_helper {
> */
> struct drm_client_display *display;
>
> + /**
> + * @client:
> + *
> + * DRM client used by the generic fbdev emulation.
> + */
> + struct drm_client_dev *client;
> +
> + /**
> + * @buffer:
> + *
> + * Framebuffer used by the generic fbdev emulation.
> + */
> + struct drm_client_buffer *buffer;
> +
> const struct drm_fb_helper_funcs *funcs;
> struct fb_info *fbdev;
> u32 pseudo_palette[17];
> @@ -219,6 +233,7 @@ struct drm_fb_helper {
> .fb_ioctl = drm_fb_helper_ioctl
>
> #ifdef CONFIG_DRM_FBDEV_EMULATION
> +int drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp);
> void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper,
> const struct drm_fb_helper_funcs *funcs);
> int drm_fb_helper_init(struct drm_device *dev,
> @@ -297,6 +312,11 @@ void drm_fb_helper_fbdev_teardown(struct drm_device *dev);
> void drm_fb_helper_lastclose(struct drm_device *dev);
> void drm_fb_helper_output_poll_changed(struct drm_device *dev);
> #else
> +static inline int
> +drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
> +{
> +}
> +
> static inline void drm_fb_helper_prepare(struct drm_device *dev,
> struct drm_fb_helper *helper,
> const struct drm_fb_helper_funcs *funcs)
> --
> 2.15.1
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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