| Message ID | 20220725145838.8412-1-alanjian85@outlook.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] hw/display/bcm2835_fb: Fix framebuffer allocation address | expand |
On Mon, 25 Jul 2022 at 16:06, Alan Jian <alanjian85@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
diff --git a/hw/display/bcm2835_fb.c b/hw/display/bcm2835_fb.c index 088fc3d51c..a05277674f 100644 --- a/hw/display/bcm2835_fb.c +++ b/hw/display/bcm2835_fb.c @@ -279,8 +279,7 @@ static void bcm2835_fb_mbox_push(BCM2835FBState *s, uint32_t value) newconf.xoffset = ldl_le_phys(&s->dma_as, value + 24); newconf.yoffset = ldl_le_phys(&s->dma_as, value + 28); - newconf.base = s->vcram_base | (value & 0xc0000000); - newconf.base += BCM2835_FB_OFFSET; + newconf.base = s->vcram_base + BCM2835_FB_OFFSET; /* Copy fields which we don't want to change from the existing config */ newconf.pixo = s->config.pixo;
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 Signed-off-by: Alan Jian <alanjian85@outlook.com> --- This patch is v2 because the previous one is signed by my username, not my full name, which is not allowed in the submission rule of QEMU. hw/display/bcm2835_fb.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)