On Wed, Apr 13, 2022 at 4:24 AM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote: > > Create a platform device for each OF-declared framebuffer and have > offb bind to these devices. Allows for real hot-unplugging and other > drivers besides offb. > > Originally, offb created framebuffer devices while initializing its > module by parsing the OF device tree. No actual Linux device was set > up. This tied OF framebuffers to offb and makes writing other drivers > for the OF framebuffers complicated. The absence of a Linux device > prevented real hot-unplugging. Adding a distinct platform device for > each OF framebuffer solves both problems. Specifically, a DRM drivers > can now provide graphics output with modern userspace. > > Some of the offb init code is now located in the OF initialization. > There's now also an implementation of of_platform_default_populate_init(), > which was missing before. The OF side creates different devices for > either OF display nodes or bootx displays as they require different > handling by the driver. The offb drivers picks up each type of device > and runs the appropriate fbdev initialization. > > Tested with OF display nodes on qemu's ppc64le target. > > Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> > --- > drivers/of/platform.c | 73 ++++++++++++++++++++++++++-- > drivers/video/fbdev/offb.c | 98 +++++++++++++++++++++++++------------- > 2 files changed, 134 insertions(+), 37 deletions(-) > > diff --git a/drivers/of/platform.c b/drivers/of/platform.c > index a16b74f32aa9..4c63b9a73587 100644 > --- a/drivers/of/platform.c > +++ b/drivers/of/platform.c > @@ -447,6 +447,60 @@ int of_platform_bus_probe(struct device_node *root, > } > EXPORT_SYMBOL(of_platform_bus_probe); > > +static int __init of_platform_populate_framebuffers(void) > +{ > + struct device_node *boot_display = NULL; > + struct device_node *node; > + struct platform_device *dev; > + int ret; > + > + node = of_get_compatible_child(of_chosen, "simple-framebuffer"); > + of_platform_device_create(node, NULL, NULL); > + of_node_put(node); > + The rest is PPC only, so bail out here if !PPC. > + /* Check if we have a MacOS display without a node spec */ > + if (of_get_property(of_chosen, "linux,bootx-noscreen", NULL)) { > + /* > + * The old code tried to work out which node was the MacOS > + * display based on the address. I'm dropping that since the > + * lack of a node spec only happens with old BootX versions > + * (users can update) and with this code, they'll still get > + * a display (just not the palette hacks). > + */ > + dev = platform_device_alloc("bootx-noscreen", 0); > + if (WARN_ON(!dev)) > + return -ENOMEM; > + ret = platform_device_add(dev); > + if (WARN_ON(ret)) { > + platform_device_put(dev); > + return ret; > + } > + } > + > + /* > + * For OF framebuffers, first create the device for the boot display, > + * then for the other framebuffers. Only fail for the boot display; > + * ignore errors for the rest. > + */ > + for_each_node_by_type(node, "display") { > + if (!of_get_property(node, "linux,opened", NULL) || > + !of_get_property(node, "linux,boot-display", NULL)) > + continue; > + dev = of_platform_device_create(node, "of-display", NULL); > + if (WARN_ON(!dev)) > + return -ENOMEM; > + boot_display = node; > + break; > + } > + for_each_node_by_type(node, "display") { > + if (!of_get_property(node, "linux,opened", NULL) || node == boot_display) > + continue; > + of_platform_device_create(node, "of-display", NULL); > + } > + > + return 0; > +} > + > /** > * of_platform_populate() - Populate platform_devices from device tree data > * @root: parent of the first level to probe or NULL for the root of the tree > @@ -541,9 +595,7 @@ static int __init of_platform_default_populate_init(void) > of_node_put(node); > } > > - node = of_get_compatible_child(of_chosen, "simple-framebuffer"); > - of_platform_device_create(node, NULL, NULL); > - of_node_put(node); > + of_platform_populate_framebuffers(); > > /* Populate everything else. */ > of_platform_default_populate(NULL, NULL, NULL); I'm pretty sure it's just this call that's the problem for PPC though none of the above existed when adding this caused a regression. Can we remove the ifdef and just make this call conditional on !IS_ENABLED(CONFIG_PPC). > @@ -551,6 +603,20 @@ static int __init of_platform_default_populate_init(void) > return 0; > } > arch_initcall_sync(of_platform_default_populate_init); > +#else > +static int __init of_platform_default_populate_init(void) > +{ > + device_links_supplier_sync_state_pause(); > + > + if (!of_have_populated_dt()) > + return -ENODEV; > + > + of_platform_populate_framebuffers(); > + > + return 0; > +} > +arch_initcall_sync(of_platform_default_populate_init); > +#endif > > static int __init of_platform_sync_state_init(void) > { > @@ -558,7 +624,6 @@ static int __init of_platform_sync_state_init(void) > return 0; > } > late_initcall_sync(of_platform_sync_state_init); > -#endif > > int of_platform_device_destroy(struct device *dev, void *data) > {