* David Herrmann <dh.herrmann@xxxxxxxxx> wrote: > Hi > > On Wed, Dec 18, 2013 at 8:42 AM, Takashi Iwai <tiwai@xxxxxxx> wrote: > > Hi, > > > > with the recent enablement of simplefb on x86, cirrusdrmfb on QEMU/KVM > > gets broken now, as reported at: > > https://bugzilla.novell.com/show_bug.cgi?id=855821 > > > > The cirrus VGA resource is reserved at first as "BOOTFB" in > > arch/x86/kernel/sysfb_simplefb.c, which is taken by simplefb platform > > device. This resource is, however, never released until the platform > > device is destroyed, and the framebuffer switching doesn't trigger > > it. It calls fb's destroy callback, at most. Then, cirrus driver > > tries to assign the resource, fails and gives up, resulting in a > > complete blank screen. > > > > The same problem should exist on other KMS drivers like mgag200 or > > ast, not only cirrus. Intel graphics doesn't hit this problem just > > because the reserved iomem by BOOTFB isn't required by i915 driver. > > > > The patch below is a quick attempt to solve the issue. It adds a new > > API function for releasing resources of platform_device, and call it > > in destroy op of simplefb. But, forcibly releasing resources of a > > parent device doesn't sound like a correct design. We may take such > > as a band aid, but definitely need a more fundamental fix. > > > > Any thoughts? > > That bug always existed, simplefb is just the first driver to hit it > (vesafb/efifb didn't use resources). I'm aware of the issue but as a > workaround you can simply disable CONFIG_X86_SYSFB. That restores > the old behavior. This looks like a regression, so we'll either need a fix or we'll have to mark CONFIG_X86_SYSFB as CONFIG_BROKEN. > As a proper fix, I'd propose something like: > dev = platform_find_device("platform-framebuffer"); > platform_remove_device(dev); > > And we wrap this as: > sysfb_remove_framebuffers() > in arch/x86/kernel/sysfb.c > > This should cause a ->remove() event for the platform-driver and > correctly release the resources. Comments? > I will try to write a patch and send it later. A fix would be awesome. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
