hw/display/bcm2835_fb: Remove unnecessary offset

[PATCH] hw/display/bcm2835_fb: Remove unnecessary offset

alanjian85 posted 1 patch 1 year, 9 months ago

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git fetch https://github.com/patchew-project/qemu tags/patchew/20220721081544.38228-1-alanjian85@outlook.com

Maintainers: Peter Maydell <peter.maydell@linaro.org>, "Philippe Mathieu-Daudé" <f4bug@amsat.org>

hw/display/bcm2835_fb.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

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[PATCH] hw/display/bcm2835_fb: Remove unnecessary offset

Posted by alanjian85 1 year, 9 months ago

This patch fixes the 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: alanjian85 <alanjian85@outlook.com>
---
 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;
-- 
2.34.1