On Thu, Dec 14, 2017 at 08:10:03PM +0100, Noralf Trønnes wrote:
> Add helpers to setup and teardown fbdev emulation.
>
> Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_fb_helper.c | 106 ++++++++++++++++++++++++++++++++++++++++
> include/drm/drm_fb_helper.h | 25 ++++++++++
> 2 files changed, 131 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 04a3a5ce370a..823fc8f50d85 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -2729,6 +2729,112 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
> }
> EXPORT_SYMBOL(drm_fb_helper_hotplug_event);
>
> +/**
> + * drm_fb_helper_fbdev_setup() - Setup fbdev emulation
> + * @dev: DRM device
> + * @fb_helper: fbdev helper structure to set up
> + * @funcs: fbdev helper functions
> + * @preferred_bpp: Preferred bits per pixel for the device.
> + * @dev->mode_config.preferred_depth is used if this is zero.
> + * @max_conn_count: Maximum number of connectors.
> + * @dev->mode_config.num_connector is used if this is zero.
> + *
> + * This function sets up fbdev emulation and registers fbdev for access by
> + * userspace. If all connectors are disconnected, setup is deferred to the next
> + * time drm_fb_helper_hotplug_event() is called.
> + * The caller must to provide a &drm_fb_helper_funcs->fb_probe callback
> + * function.
I think we should be a bit clearer when it's not advisable to use this
helper because there are issues:
- when connectors can be hotplugged (e.g. dp mst). For that case you need
to init the fbdev before you enabling hotplugging, but call
initial_config after you've enabled hotplugging. Otherwise there's a
posssible race window.
- when there's anything else that mus be done before we do the fbdev
registration, e.g. defio_init.
So still not 100% sure this will help you all that much, but it's also not
an unreasonable idea.
Assuming we can agree on the ceveats and how do document them:
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> + *
> + * See also: drm_fb_helper_initial_config()
> + *
> + * Returns:
> + * Zero on success or negative error code on failure.
> + */
> +int drm_fb_helper_fbdev_setup(struct drm_device *dev,
> + struct drm_fb_helper *fb_helper,
> + const struct drm_fb_helper_funcs *funcs,
> + unsigned int preferred_bpp,
> + unsigned int max_conn_count)
> +{
> + int ret;
> +
> + if (!preferred_bpp)
> + preferred_bpp = dev->mode_config.preferred_depth;
> + if (!preferred_bpp)
> + preferred_bpp = 32;
> +
> + if (!max_conn_count)
> + max_conn_count = dev->mode_config.num_connector;
> + if (!max_conn_count) {
> + DRM_DEV_ERROR(dev->dev, "No connectors\n");
> + return -EINVAL;
> + }
> +
> + drm_fb_helper_prepare(dev, fb_helper, funcs);
> +
> + ret = drm_fb_helper_init(dev, fb_helper, max_conn_count);
> + if (ret < 0) {
> + DRM_DEV_ERROR(dev->dev, "Failed to initialize fbdev helper\n");
> + return ret;
> + }
> +
> + ret = drm_fb_helper_single_add_all_connectors(fb_helper);
> + if (ret < 0) {
> + DRM_DEV_ERROR(dev->dev, "Failed to add connectors\n");
> + goto err_drm_fb_helper_fini;
> + }
> +
> + if (!drm_drv_uses_atomic_modeset(dev))
> + drm_helper_disable_unused_functions(dev);
> +
> + ret = drm_fb_helper_initial_config(fb_helper, preferred_bpp);
> + if (ret < 0) {
> + DRM_DEV_ERROR(dev->dev, "Failed to set fbdev configuration\n");
> + goto err_drm_fb_helper_fini;
> + }
> +
> + return 0;
> +
> +err_drm_fb_helper_fini:
> + drm_fb_helper_fini(fb_helper);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(drm_fb_helper_fbdev_setup);
> +
> +/**
> + * drm_fb_helper_fbdev_teardown - Tear down fbdev emulation
> + * @dev: DRM device
> + *
> + * This function unregisters fbdev if not already done and cleans up the
> + * associated resources including the &drm_framebuffer.
> + * The driver is responsible for freeing the &drm_fb_helper structure which is
> + * stored in &drm_device->fb_helper. Do note that this pointer has been cleared
> + * when this function returns.
> + *
> + * In order to support device removal/unplug while file handles are still open,
> + * drm_fb_helper_unregister_fbi() should be called on device removal and
> + * drm_fb_helper_fbdev_teardown() in the &drm_driver->release callback when
> + * file handles are closed.
> + */
> +void drm_fb_helper_fbdev_teardown(struct drm_device *dev)
> +{
> + struct drm_fb_helper *fb_helper = dev->fb_helper;
> +
> + if (!fb_helper)
> + return;
> +
> + /* Unregister if it hasn't been done already */
> + if (fb_helper->fbdev && fb_helper->fbdev->dev)
> + drm_fb_helper_unregister_fbi(fb_helper);
> +
> + drm_fb_helper_fini(fb_helper);
> +
> + if (fb_helper->fb)
> + drm_framebuffer_remove(fb_helper->fb);
> +}
> +EXPORT_SYMBOL(drm_fb_helper_fbdev_teardown);
> +
> /**
> * drm_fb_helper_lastclose - DRM driver lastclose helper for fbdev emulation
> * @dev: DRM device
> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> index 1bd624579db7..aa78ac3b8ad0 100644
> --- a/include/drm/drm_fb_helper.h
> +++ b/include/drm/drm_fb_helper.h
> @@ -320,6 +320,13 @@ int drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper, struct drm_
> int drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper,
> struct drm_connector *connector);
>
> +int drm_fb_helper_fbdev_setup(struct drm_device *dev,
> + struct drm_fb_helper *fb_helper,
> + const struct drm_fb_helper_funcs *funcs,
> + unsigned int preferred_bpp,
> + unsigned int max_conn_count);
> +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
> @@ -525,6 +532,24 @@ drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper,
> return 0;
> }
>
> +static inline int
> +drm_fb_helper_fbdev_setup(struct drm_device *dev,
> + struct drm_fb_helper *fb_helper,
> + const struct drm_fb_helper_funcs *funcs,
> + unsigned int preferred_bpp,
> + unsigned int max_conn_count)
> +{
> + /* So drivers can use it to free the struct */
> + dev->fb_helper = fb_helper;
> +
> + return 0;
> +}
> +
> +static inline void drm_fb_helper_fbdev_teardown(struct drm_device *dev)
> +{
> + dev->fb_helper = NULL;
> +}
> +
> static inline void drm_fb_helper_lastclose(struct drm_device *dev)
> {
> }
> --
> 2.14.2
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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