On Mon, 25 Jul 2022 at 16:06, Alan Jian <alanjia...@gmail.com> wrote: > > This patch fixes the dedicated framebuffer mailbox interface(marked as > deprecated in official docs, but can still be fixed for emulation purposes) > by removing unneeded offset to make it works like buffer allocate tag in > bcm2835_property interface[1], some baremetal applications like the > Screen01/Screen02 examples from Baking Pi tutorial[2] didn't work > before this patch. > > [1] https://github.com/qemu/qemu/blob/master/hw/misc/bcm2835_property.c#L158 > [2] https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/screen01.html
Thanks. If examples which work on real hardware don't work on QEMU then we presumably have a bug, and the documentation of this fb mbox https://github.com/raspberrypi/firmware/wiki/Mailbox-framebuffer-interface doesn't say anything about using the top bits of the config-struct address for anything, so the current code definitely looks wrong. This was the only place where we ever changed the config struct's .base field to something other than s->vcram_base + BCM2835_FB_OFFSET. If the .base field is now effectively constant then it's pointless and we can clean things up a bit by getting rid of it. I'll send a followup patch at some point. Applied to target-arm.next, thanks. (I tweaked the commit message slightly.) -- PMM
