Men Have Been On The Moon

其實這是一篇三年前 po 過的文章，但是不知為何好像被 FB 吃文了（果然想保存的東西不能放 FB 呀...）

話說當年剛出社會，第一份工作在 USI，被 assign 了一個 IC module diagnostic 的 project，要用 UBoot 去測 Hardware。對初試啼聲的我來說還滿難的，所幸 UBoot 的進入障礙不高，後來有順利完成。

後來，主管 assign 了另一個相當難的 task：
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Dear Qian-Hao

As I know, most of OMAP4 CPU board testing functions are completed by yourself, well done.
But here I would like you to dig a function "HDMI". It is the only one we cannot test as my understanding.
==

困難點在於... TI 沒有公開 OMAP4 的 HDMI 資料，所以我連 register address table 都沒得看，唯一可以參考的資料是 TI release 的 Linux kernel BSP......

對當時的我來說簡直就是不可能的任務呀（即便是現在依然覺得很難）
走投無路的菜鳥千只能硬著頭皮去 TI 的論壇上面求救。
http://comments.gmane.org/gmane.comp.embedded.pandaboard/6466
然而，也有 TI 內部的人回信了，而且回得很有個性。

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Re: Is it possible to send HDMI signal from u-boot on PandaBoard?

Qiao wrote:
> Hi everyone,
>
> I'm working on modifying u-boot source code for testing HDMI function on PandaBoard (CPU is TI OMAP4430).
> There seems no related information on the web.
>
> I've studied the android kernel source, and it confused me that the linux video driver access lots of
registers which
> are not mentioned in the OMAP4430 Technical Reference Manual.

yes, the HDMI part of the omap4 is not openly documented.

> However, the driver of android is so huge and complicated that I can't port it on u-boot.

you mean the linux driver.

> Can anyone tell me how to control HDMI module inside OMAP4430 by u-boot? I just want to do some tiny tasks,
such as
> showing the Android logo or filling the screen of specified color.

regardless of what you show you need to setup the hdmi part of the omap4
correctly. so I fear you will have to replicate most of the linux
hdmi driver in uboot.

> Maybe give some suggestions or directions for me to study is OK.

study the linux driver, it's the best (open) documentation you
can get. Or talk to your TI contact to get the HDMI docs
under NDA...

> Or is it impossible? and why?

men have been on the moon
==