From 5865d99fe88d8c8fa437c18c6b63fb2a8165634f Mon Sep 17 00:00:00 2001 From: Alan Jian Date: Mon, 25 Jul 2022 22:58:39 +0800 Subject: [PATCH] hw/display/bcm2835_fb: Fix framebuffer allocation address This patch fixes the dedicated framebuffer mailbox interface by removing an unneeded offset. This means that we pick the framebuffer address in the same way that we do if the guest code uses the buffer allocate mechanism of the bcm2835_property interface (case 0x00040001: /* Allocate buffer */ in bcm2835_property.c). The documentation of this mailbox interface doesn't say anything about using parts of the request buffer address to affect the chosen framebuffer address: https://github.com/raspberrypi/firmware/wiki/Mailbox-framebuffer-interface Some baremetal applications like the Screen01/Screen02 examples from Baking Pi tutorial[1] didn't work before this patch. [1] https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/screen01.html Signed-off-by: Alan Jian Message-id: 20220725145838.8412-1-alanjian85@outlook.com [PMM: tweaked commit message] Reviewed-by: Peter Maydell Signed-off-by: Peter Maydell --- hw/display/bcm2835_fb.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) 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;