From 345acc443905eda8008a1d328dd89b73c4a3f89e Mon Sep 17 00:00:00 2001 From: SamJakob Date: Sat, 13 Jul 2024 17:03:53 +0100 Subject: [PATCH] hw/display/bcm2835_fb: fix fb_use_offsets condition MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Message-id: 20240713160353.62410-1-me@samjakob.com Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Peter Maydell --- 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; } -- 2.39.5