Re: Display Architecture and Bring Up in UEFI

["Ni, Ruiyu" <ruiyu.ni@Intel.com>]

On 11/23/2018 5:19 PM, Laszlo Ersek wrote:
> On 11/23/18 07:27, prabin ca wrote:
>> Hi Team,
>>
>> I’m new to UEFI and display interface in UEFI. I would like to have deep dive into how display is working in UEFI (display architecture) and how display is have been bring up (porting of display panel in a any platform in general ).
>>
>> Please help me with sample codes and necessary documents. I would like to get knowledge about display bring up and display architecture in UEFI
> 
> The driver writers' guide and the UEFI spec have relevant chapters on
> this. I think it's best to start reading the former, at "23 Graphics
> Driver Design Guidelines"; that part will give you the pointers to the
> rest as well.
> 
> https://github.com/tianocore/tianocore.github.io/wiki/UEFI-Driver-Writer%27s-Guide
> 
> 
> For a (hopefully educational) example, I refer you to
> OvmfPkg/VirtioGpuDxe. In the series that first added this driver to
> edk2, I managed to construct the driver in stages such that each stage
> would build and even function, at the level expected from that stage. In
> particular, commit a2a4fa66701d ("OvmfPkg/VirtioGpuDxe: introduce with
> Component Name 2 and Driver Binding", 2016-09-01) could prove helpful,
> as it adds the skeleton of the driver, mostly without VirtIo GPU specifics.
> 
> 
> In addition, you might want to look into the generic
> 
>    MdeModulePkg/Universal/Console/GraphicsOutputDxe
> 
> driver. A platform may be able to incorporate that driver without any
> changes, and control it by first producing the two HOBs in the PEI phase
> that the driver consumes:
> 
>    MdePkg/Include/Guid/GraphicsInfoHob.h
> 
> (... Interestingly, due to the fact that this header file is under
> MdePkg and not MdeModulePkg, I've just learned, from the related commit
> messages, that the PEI phase has standardized graphics support,
> described in the PI spec. From the following two commit messages:
> 
> - 697c6cf32693 ("MdePkg: Add PI 1.4 Graphics HOB and PPI header files",
> 2015-04-28)
> 
> - 2af538fbf667 ("MdeModulePkg: Add GraphicsOutputDxe driver.", 2016-10-12)
> 
> it appears that enabling graphics support in the PEI phase could be a
> *requirement* for using GraphicsOutputDxe in the DXE phase. That might
> or might not match your use case, so perhaps it will prevent you from
> using GraphicsOutputDxe. I'm not sure.)

Yes. GraphicsOutputDxe layers on the HOB produced in PEI phase to 
provide GOP protocol.


> 
> Thanks
> Laszlo
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-- 
Thanks,
Ray