On Tue, May 03, 2022 at 09:15:40AM +0200, Javier Martinez Canillas wrote:
> Indicate to fbdev subsystem that the registered framebuffer is provided by
> the system firmware, so that it can handle accordingly. For example, would
> unregister the FB devices if asked to remove the conflicting framebuffers.
>
> Add a new DRM_FB_FW field to drm_fbdev_generic_setup() options parameter.
> Drivers can use this to indicate the FB helper initialization that the FB
> registered is provided by the firmware, so it can be configured as such.
>
> Suggested-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
> Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
>
> Changes in v3:
> - Drop the firmware local variable (Laurent Pinchart).
> - Use DRM_FB_OPTION() since DRM_FB_SET_OPTION() got renamed (kernel test robot).
Just for the record what I brought up on irc already:
FBINFO_MISC_FIRMWARE is purely an internal flag with no uapi impact, and
it's only to control whether we nuke this from
remove_conflicting_framebuffer or not. Since simpledrm only ever binds
against sysfb I think it'd be cleaner to only rely on that, and relegate
that entire FBINFO_MISC_FIRMWARE misc hack to the fbdev dungeons and let
it quietly wither away there.
Also I'm not a huge fan of these midlayer flags in general :-)
-Daniel
>
> drivers/gpu/drm/drm_fb_helper.c | 8 ++++++++
> drivers/gpu/drm/tiny/simpledrm.c | 2 +-
> include/drm/drm_fb_helper.h | 10 ++++++++++
> 3 files changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 52042ba1e4cf..28b21858b726 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -1891,6 +1891,10 @@ __drm_fb_helper_initial_config_and_unlock(struct drm_fb_helper *fb_helper,
> /* don't leak any physical addresses to userspace */
> info->flags |= FBINFO_HIDE_SMEM_START;
>
> + /* Indicate that the framebuffer is provided by the firmware */
> + if (fb_helper->firmware)
> + info->flags |= FBINFO_MISC_FIRMWARE;
> +
> /* Need to drop locks to avoid recursive deadlock in
> * register_framebuffer. This is ok because the only thing left to do is
> * register the fbdev emulation instance in kernel_fb_helper_list. */
> @@ -2512,6 +2516,8 @@ static const struct drm_client_funcs drm_fbdev_client_funcs = {
> *
> * * DRM_FB_BPP: bits per pixel for the device. If the field is not set,
> * @dev->mode_config.preferred_depth is used instead.
> + * * DRM_FB_FW: if the framebuffer for the device is provided by the
> + * system firmware.
> *
> * This function sets up generic fbdev emulation for drivers that supports
> * dumb buffers with a virtual address and that can be mmap'ed.
> @@ -2569,6 +2575,8 @@ void drm_fbdev_generic_setup(struct drm_device *dev, const unsigned int options)
> if (!fb_helper->preferred_bpp)
> fb_helper->preferred_bpp = 32;
>
> + fb_helper->firmware = DRM_FB_GET_OPTION(DRM_FB_FW, options);
> +
> ret = drm_fbdev_client_hotplug(&fb_helper->client);
> if (ret)
> drm_dbg_kms(dev, "client hotplug ret=%d\n", ret);
> diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
> index f5b8e864a5cd..f6f1c5e108b2 100644
> --- a/drivers/gpu/drm/tiny/simpledrm.c
> +++ b/drivers/gpu/drm/tiny/simpledrm.c
> @@ -901,7 +901,7 @@ static int simpledrm_probe(struct platform_device *pdev)
> if (ret)
> return ret;
>
> - drm_fbdev_generic_setup(dev, 0);
> + drm_fbdev_generic_setup(dev, DRM_FB_OPTION(DRM_FB_FW, 1));
>
> return 0;
> }
> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> index 5fc41cf0c987..5a17af423944 100644
> --- a/include/drm/drm_fb_helper.h
> +++ b/include/drm/drm_fb_helper.h
> @@ -44,6 +44,7 @@ enum mode_set_atomic {
> };
>
> #define DRM_FB_BPP_MASK GENMASK(7, 0)
> +#define DRM_FB_FW_MASK GENMASK(8, 8)
>
> /* Using the GNU statement expression extension */
> #define DRM_FB_OPTION(option, value) \
> @@ -197,6 +198,15 @@ struct drm_fb_helper {
> * See also: @deferred_setup
> */
> int preferred_bpp;
> +
> + /**
> + * @firmware:
> + *
> + * Set if the driver indicates to the FB helper initialization that the
> + * framebuffer for the device being registered is provided by firmware,
> + * so that it can pass this on when registering the framebuffer device.
> + */
> + bool firmware;
> };
>
> static inline struct drm_fb_helper *
> --
> 2.35.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
