Hello Rao,
On 30.07.21 13:53, Rao G wrote:
trying to see the MMIO or VBIOS data when a external display device is plugged/unplugged with DP/HDMI interface, which MMIO register is set or cleared
I think you are looking at the right register (last one below).
Any inputs are appreciated, some of the registers tried on Port B/Port C are given below. when Display is connected and when Display is not connected, both these instances return the same data. Looking for register/bit that sets/clears when external display is connected/disconnected
printk(BIOS_DEBUG, "Intel Gfx BAR GTTMMADR\n"); printk(BIOS_DEBUG, " DP_B %X\n", read32(bar+0x180000+0x64100)); printk(BIOS_DEBUG, " DP_C %X\n", read32(bar+0x180000+0x64200)); printk(BIOS_DEBUG, " HDMIC %X\n", read32(bar+0x180000+0x61160)); printk(BIOS_DEBUG, " HDMIB %X\n", read32(bar+0x180000+0x61140)); printk(BIOS_DEBUG, " Hotplug control %X\n", read32(bar+0x180000+0x61164)); printk(BIOS_DEBUG, " pipeA control %X\n", read32(bar+0x180000+0x61204)); printk(BIOS_DEBUG, " pipeB control %X\n", read32(bar+0x180000+0x61304)); printk(BIOS_DEBUG, " porthot plug stat %X\n", read32(bar+0x180000+0x61114));
According to the datasheet, the bits in this register should change but only if enabled in PORT_HOTPLUG_EN (0x61110).
Nico
NB. There is also libgfxinit support under review [1]. In case you are trying to do some native graphics init ;)
[1] https://review.coreboot.org/q/topic:%2522baytrail-libgfxinit%2522