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	drm/fb-helper: Finish the generic fbdev emulation
This adds a drm_fbdev_generic_setup() function that sets up generic fbdev emulation with client callbacks for restore, hotplug and unregister. Signed-off-by: Noralf Trønnes <noralf@tronnes.org> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20180703160354.59955-7-noralf@tronnes.org
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					 2 changed files with 124 additions and 0 deletions
				
			
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			@ -67,6 +67,9 @@ static DEFINE_MUTEX(kernel_fb_helper_lock);
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 * helper functions used by many drivers to implement the kernel mode setting
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 * interfaces.
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 *
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 * Drivers that support a dumb buffer with a virtual address and mmap support,
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 * should try out the generic fbdev emulation using drm_fbdev_generic_setup().
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 *
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 * Setup fbdev emulation by calling drm_fb_helper_fbdev_setup() and tear it
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 * down by calling drm_fb_helper_fbdev_teardown().
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 *
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			@ -3118,6 +3121,120 @@ int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
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}
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EXPORT_SYMBOL(drm_fb_helper_generic_probe);
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static const struct drm_fb_helper_funcs drm_fb_helper_generic_funcs = {
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	.fb_probe = drm_fb_helper_generic_probe,
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};
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static void drm_fbdev_client_unregister(struct drm_client_dev *client)
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{
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	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
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	if (fb_helper->fbdev) {
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		drm_fb_helper_unregister_fbi(fb_helper);
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		/* drm_fbdev_fb_destroy() takes care of cleanup */
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		return;
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	}
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	/* Did drm_fb_helper_fbdev_setup() run? */
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	if (fb_helper->dev)
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		drm_fb_helper_fini(fb_helper);
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	drm_client_release(client);
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	kfree(fb_helper);
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}
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static int drm_fbdev_client_restore(struct drm_client_dev *client)
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{
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	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
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	drm_fb_helper_restore_fbdev_mode_unlocked(fb_helper);
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	return 0;
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}
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static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
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{
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	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
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	struct drm_device *dev = client->dev;
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	int ret;
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	/* If drm_fb_helper_fbdev_setup() failed, we only try once */
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	if (!fb_helper->dev && fb_helper->funcs)
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		return 0;
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	if (dev->fb_helper)
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		return drm_fb_helper_hotplug_event(dev->fb_helper);
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	if (!dev->mode_config.num_connector)
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		return 0;
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	ret = drm_fb_helper_fbdev_setup(dev, fb_helper, &drm_fb_helper_generic_funcs,
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					fb_helper->preferred_bpp, 0);
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	if (ret) {
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		fb_helper->dev = NULL;
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		fb_helper->fbdev = NULL;
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		return ret;
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	}
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	return 0;
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}
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static const struct drm_client_funcs drm_fbdev_client_funcs = {
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	.owner		= THIS_MODULE,
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	.unregister	= drm_fbdev_client_unregister,
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	.restore	= drm_fbdev_client_restore,
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	.hotplug	= drm_fbdev_client_hotplug,
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};
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/**
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 * drm_fb_helper_generic_fbdev_setup() - Setup generic fbdev emulation
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 * @dev: DRM device
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 * @preferred_bpp: Preferred bits per pixel for the device.
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 *                 @dev->mode_config.preferred_depth is used if this is zero.
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 *
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 * This function sets up generic fbdev emulation for drivers that supports
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 * dumb buffers with a virtual address and that can be mmap'ed.
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 *
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 * Restore, hotplug events and teardown are all taken care of. Drivers that do
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 * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
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 * Simple drivers might use drm_mode_config_helper_suspend().
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 *
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 * Drivers that set the dirty callback on their framebuffer will get a shadow
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 * fbdev buffer that is blitted onto the real buffer. This is done in order to
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 * make deferred I/O work with all kinds of buffers.
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 *
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 * This function is safe to call even when there are no connectors present.
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 * Setup will be retried on the next hotplug event.
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 *
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 * Returns:
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 * Zero on success or negative error code on failure.
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 */
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int drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
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{
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	struct drm_fb_helper *fb_helper;
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	int ret;
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	if (!drm_fbdev_emulation)
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		return 0;
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	fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
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	if (!fb_helper)
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		return -ENOMEM;
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	ret = drm_client_new(dev, &fb_helper->client, "fbdev", &drm_fbdev_client_funcs);
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	if (ret) {
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		kfree(fb_helper);
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		return ret;
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	}
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	fb_helper->preferred_bpp = preferred_bpp;
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	drm_fbdev_client_hotplug(&fb_helper->client);
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	return 0;
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}
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EXPORT_SYMBOL(drm_fbdev_generic_setup);
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/* The Kconfig DRM_KMS_HELPER selects FRAMEBUFFER_CONSOLE (if !EXPERT)
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 * but the module doesn't depend on any fb console symbols.  At least
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 * attempt to load fbcon to avoid leaving the system without a usable console.
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			@ -354,6 +354,7 @@ void drm_fb_helper_output_poll_changed(struct drm_device *dev);
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int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
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				struct drm_fb_helper_surface_size *sizes);
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int drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp);
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#else
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static inline void drm_fb_helper_prepare(struct drm_device *dev,
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					struct drm_fb_helper *helper,
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			@ -595,6 +596,12 @@ drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
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	return 0;
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}
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static inline int
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drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
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{
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	return 0;
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}
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#endif
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static inline int
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