Mostly this is just adding extensive docs for the callbacks, but also
a few other additions.
v2: Use FIXME comments to annotate helper hooks that should be
replaced.
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
include/drm/drm_fb_helper.h | 92 ++++++++++++++++++++++++++++++++++++++-------
1 file changed, 79 insertions(+), 13 deletions(-)
diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index 87b090c4b730..5ce033e36039 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -74,25 +74,76 @@ struct drm_fb_helper_surface_size {
/**
* struct drm_fb_helper_funcs - driver callbacks for the fbdev emulation library
- * @gamma_set: Set the given gamma lut register on the given crtc.
- * @gamma_get: Read the given gamma lut register on the given crtc, used to
- * save the current lut when force-restoring the fbdev for e.g.
- * kdbg.
- * @fb_probe: Driver callback to allocate and initialize the fbdev info
- * structure. Furthermore it also needs to allocate the drm
- * framebuffer used to back the fbdev.
- * @initial_config: Setup an initial fbdev display configuration
*
* Driver callbacks used by the fbdev emulation helper library.
*/
struct drm_fb_helper_funcs {
+ /**
+ * @gamma_set:
+ *
+ * Set the given gamma lut register on the given crtc.
+ *
+ * This callback is optional.
+ *
+ * FIXME:
+ *
+ * This callback is functionally redundant with the core gamma table
+ * support and simply exists because the fbdev hasn't yet been
+ * refactored to use the core gamma table interfaces.
+ */
void (*gamma_set)(struct drm_crtc *crtc, u16 red, u16 green,
u16 blue, int regno);
+ /**
+ * @gamma_get:
+ *
+ * Read the given gamma lut register on the given crtc, used to save the
+ * current lut when force-restoring the fbdev for e.g. kdbg.
+ *
+ * This callback is optional.
+ *
+ * FIXME:
+ *
+ * This callback is functionally redundant with the core gamma table
+ * support and simply exists because the fbdev hasn't yet been
+ * refactored to use the core gamma table interfaces.
+ */
void (*gamma_get)(struct drm_crtc *crtc, u16 *red, u16 *green,
u16 *blue, int regno);
+ /**
+ * @fb_probe:
+ *
+ * Driver callback to allocate and initialize the fbdev info structure.
+ * Furthermore it also needs to allocate the drm framebuffer used to
+ * back the fbdev.
+ *
+ * This callback is mandatory.
+ *
+ * RETURNS:
+ *
+ * The driver should return 0 on success and a negative error code on
+ * failure.
+ */
int (*fb_probe)(struct drm_fb_helper *helper,
struct drm_fb_helper_surface_size *sizes);
+
+ /**
+ * @initial_config:
+ *
+ * Driver callback to setup an initial fbdev display configuration.
+ * Drivers can use this callback to tell the fbdev emulation what the
+ * preferred initial configuration is. This is useful to implement
+ * smooth booting where the fbdev (and subsequently all userspace) never
+ * changes the mode, but always inherits the existing configuration.
+ *
+ * This callback is optional.
+ *
+ * RETURNS:
+ *
+ * The driver should return true if a suitable initial configuration has
+ * been filled out and false when the fbdev helper should fall back to
+ * the default probing logic.
+ */
bool (*initial_config)(struct drm_fb_helper *fb_helper,
struct drm_fb_helper_crtc **crtcs,
struct drm_display_mode **modes,
@@ -105,18 +156,22 @@ struct drm_fb_helper_connector {
};
/**
- * struct drm_fb_helper - helper to emulate fbdev on top of kms
+ * struct drm_fb_helper - main structure to emulate fbdev on top of kms
* @fb: Scanout framebuffer object
* @dev: DRM device
* @crtc_count: number of possible CRTCs
* @crtc_info: per-CRTC helper state (mode, x/y offset, etc)
* @connector_count: number of connected connectors
* @connector_info_alloc_count: size of connector_info
+ * @connector_info: array of per-connector information
* @funcs: driver callbacks for fb helper
* @fbdev: emulated fbdev device info struct
* @pseudo_palette: fake palette of 16 colors
- * @kernel_fb_list: list_head in kernel_fb_helper_list
- * @delayed_hotplug: was there a hotplug while kms master active?
+ *
+ * This is the main structure used by the fbdev helpers. Drivers supporting
+ * fbdev emulation should embedded this into their overall driver structure.
+ * Drivers must also fill out a struct &drm_fb_helper_funcs with a few
+ * operations.
*/
struct drm_fb_helper {
struct drm_framebuffer *fb;
@@ -129,10 +184,21 @@ struct drm_fb_helper {
const struct drm_fb_helper_funcs *funcs;
struct fb_info *fbdev;
u32 pseudo_palette[17];
+
+ /**
+ * @kernel_fb_list:
+ *
+ * Entry on the global kernel_fb_helper_list, used for kgdb entry/exit.
+ */
struct list_head kernel_fb_list;
- /* we got a hotplug but fbdev wasn't running the console
- delay until next set_par */
+ /**
+ * @delayed_hotplug:
+ *
+ * A hotplug was received while fbdev wasn't in control of the drm
+ * device, i.e. another kms master was active. The output configuration
+ * needs to be reprobe when fbdev is in control again.
+ */
bool delayed_hotplug;
/**
--
2.5.1
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