Maybe you are right. I would try to figure out the issue in graphics console devices.
Making edk2 do not unnecessarily re-initialize is a good idea. But the ‘flicker free’ is depend on the platform code designer. By default the flicker would always happen because of some pcds (gEfiMdeModulePkgTokenSpaceGuid.PcdVideoHorizontalResolution, gEfiMdeModulePkgTokenSpaceGuid.PcdVideoVerticalResolution). The two pcds have default value, we suggest the platform to set them to zero in the platform dsc file and that means the platform would initialize the screen resolution to the maximum. If not and the screen’s resolution is different with the default value, then the screen would flicker and set the screen to the default resolution.
For now, I didn’t find other issues in edk2 code.

Thanks,
Zhichao

From: sean.brogan via groups.io [mailto:sean.brogan=microsoft.com@groups.io]
Sent: Tuesday, April 30, 2019 9:08 AM
To: Gao; Gao, Zhichao <zhichao.gao@intel.com>; devel@edk2.groups.io
Subject: Re: [edk2-devel] [PATCH V2 2/2] MdeModulePkg/GraphicsConsoleDxe: Do not clean the screen

Zhichao,

That sounds like a bug in you graphics console devices.  If they are already initialized (by pei or other platform code) they should not start in mode -1.
For bug 1412, can we make sure all Tianocore edk2 drivers support "flicker free" and don't unncecessarly re-initialize.  Do you see other issues in edk2 code?

Thanks
Sean