ds90ub949 无法读取edid

Hi 张工：
谢谢回复。

连上HDMI Dongle，连着FPD-link，我把ds90ub949的寄存器dump出来了。
寄存器0x0c的值为0x03.

DES Error CRC error(s) during normal communication with Deserializer. This bit is cleared upon
loss of link or assertion of 0x04[5].
0: No CRC errors detected.
1: CRC error(s) detected.
If PORT1_SEL is set, this register is with reference to Port1.

Link Detect Link detect status:
0: Cable link not detected.
1: Cable link detected.
If PORT1_SEL is set, this register is with reference to Port1

可以检测到cable link 但是有CRC错误。

我再检查一下940那部分，看有什么问题，谢谢。

以下是完整的949寄存器的值。
root@salvator-x:~# i2cdump -f -y 4 0x0c
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: 18 00 00 d2 80 00 60 00 00 00 02 00 03 20 00 00
10: 00 00 00 88 00 01 fe 1e 7f 7f 01 00 00 00 01 00
20: 0b 00 25 00 00 00 00 00 01 20 20 a0 00 00 a5 5a
30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
40: 14 55 00 00 80 00 00 00 00 00 00 00 00 00 00 00
50: 97 a1 1e 00 28 0c 00 00 00 00 92 20 02 06 44 00
60: 22 02 00 00 10 00 00 00 00 00 00 00 00 00 00 00
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
c0: 00 00 a8 00 68 38 00 00 c0 00 00 00 00 00 ff 00
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
e0: 00 00 a8 00 68 38 00 00 00 00 00 00 00 00 00 00
f0: 5f 55 42 39 34 39 00 00 00 00 00 00 00 00 00 00

Hi 张工：

请问假如按照ds90ub940和ds90ub949 datasheet 中给的参考设计来设计电路的话，上电之后用默认的寄存器两个片子就可以正常工作，对吗？

BR,

Qin

您好，请问您是怎么解决的，我也遇到了这个问题。

也就是说，你把硬件改了之后就可以正常的读取949内部的edid了是吧

对。注意检查下硬件，datasheet 上有参考电路，你可以对着检查一次。

嗯，我现在是soc 通过hdmi接口接949接924再接显示屏，这个显示屏需要特定的timing,我想知道soc从949内部获取的edid中包含的timing如果和显示屏需求的不符，那我应该调整哪里

看看edid 的协议，也可以找找edid的编辑工具，工具可以帮你生成edid. 我用过 AW EDID Editor，这挺好用的。

也就是说我需要用这个工具生成我需要的EDID,然后再把这个EDID弄到DS90UB949内部的flash里面去？

如果是这样，那怎么把edid弄到949内部的flash中去呢，还有soc这边如何判断是否已经从949里面读到edid了呢

可以通过949的 DDC 通道写入。如果读不到edid的话，HDMI 信号没有输出