From: SamJakob <m...@samjakob.com>
It is common practice when implementing double-buffering on VideoCore
to do so by multiplying the height of the virtual buffer by the
number of virtual screens desired (i.e., two - in the case of
double-bufferring).
At present, this won't work in QEMU because the logic in
fb_use_offsets require that both the virtual width and height exceed
their physical counterparts.
This appears to be unintentional/a typo and indeed the comment
states; "Experimentally, the hardware seems to do this only if the
viewport size is larger than the physical screen". The
viewport/virtual size would be larger than the physical size if
either virtual dimension were larger than their physical counterparts
and not necessarily both.
Signed-off-by: SamJakob <m...@samjakob.com>
Message-id: 20240713160353.62410-1...@samjakob.com
Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org>
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
hw/display/bcm2835_fb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/display/bcm2835_fb.c b/hw/display/bcm2835_fb.c
index e40ed2d2e18..650db3da82c 100644
--- a/hw/display/bcm2835_fb.c
+++ b/hw/display/bcm2835_fb.c
@@ -145,7 +145,7 @@ static bool fb_use_offsets(BCM2835FBConfig *config)
* viewport size is larger than the physical screen. (It doesn't
* prevent the guest setting this silly viewport setting, though...)
*/
- return config->xres_virtual > config->xres &&
+ return config->xres_virtual > config->xres ||
config->yres_virtual > config->yres;
}
--
2.34.1
