Find out the device ID:
root@akaicloud:~# lspci | grep ' VGA ' | cut -d" " -f 1
0e:0d.0
You can then use this output with lspci again, forming two nested commands
lspci -v -s $(lspci | grep ' VGA ' | cut -d" " -f 1)
Output from my system:
root@akaicloud:~# lspci -v -s $(lspci | grep ' VGA ' | cut -d" " -f 1)
0e:0d.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] ES1000 (rev 02) (prog-if 00 [VGA controller])
Subsystem: Dell ES1000
Flags: bus master, VGA palette snoop, stepping, medium devsel, latency 32, IRQ 19
Memory at d8000000 (32-bit, prefetchable) [size=128M]
I/O ports at dc00 [size=256]
Memory at fc2d0000 (32-bit, non-prefetchable) [size=64K]
[virtual] Expansion ROM at fc100000 [disabled] [size=128K]
Capabilities: [50] Power Management version 2
Kernel driver in use: radeon
Kernel modules: radeonfb, radeon
prefetchable is what GPU you have. This result says 128M
