The FB address is generated by the firmware running on the GPU/VideoCore and is a "bus" address. This address is the other side of an IOMMU from the ARM upon which U-Boot is running. Use bus_to_phys() to convert this to an ARM physical address. Without this, U-Boot seems to work just fine, but once the Linux kernel boots on an RPi2, accessing the FB memory often causes a hard system hang.
This is related to: 122426d46e31 ARM: bcm2835: use phys_to_bus() for mbox 5c0beb5c58c8 usb: dwc2: use phys_to_bus/bus_to_phys 79340db7f1f6 ARM: bcm2835: implement phys_to_bus/bus_to_phys
Signed-off-by: Stephen Warren swarren@wwwdotorg.org --- drivers/video/bcm2835.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/video/bcm2835.c b/drivers/video/bcm2835.c index 7867fe3895d0..bff1fcb9eaf7 100644 --- a/drivers/video/bcm2835.c +++ b/drivers/video/bcm2835.c @@ -7,6 +7,7 @@ #include <common.h> #include <lcd.h> #include <memalign.h> +#include <phys2bus.h> #include <asm/arch/mbox.h> #include <asm/global_data.h>
@@ -103,7 +104,8 @@ void lcd_ctrl_init(void *lcdbase) panel_info.vl_row = h; panel_info.vl_bpix = LCD_COLOR16;
- gd->fb_base = msg_setup->allocate_buffer.body.resp.fb_address; + gd->fb_base = bus_to_phys( + msg_setup->allocate_buffer.body.resp.fb_address); }
void lcd_enable(void)