07-12-2016 03:39 AM
I found a bug in DisplayPort driver v5.0 with vivado 2016.2.
xdp_selftest.c table "TxResetValues" defined XDP_TX_PHY_CONFIG default value as 0x03. While I tried to read this register, it should be 0x200003. Refer to PG064 table 2-9, it should also be 0x200003.
So is the example release without testing?
07-12-2016 04:05 AM
Do you mean that you are reading a value of 0x200003 when it is expected to be 0x03?
The PG sure mentions that this should be 0x03 and the driver too mentions this correctly as 0x03.
07-12-2016 04:21 AM
PG064 page31 described the bit 21 of reg 0x200 as below:
 – Set to 1 to enable the 8B10B coding. Default is 1. SW should not unset this bit for normal operation of TX PHY.
So I considered that bit 21 should be 1 by default.
07-12-2016 04:57 AM
As mentioned in the PG this bit should not be change during normal operation. However during reset (which is not normal operation) it is fine to reset this as we do not care about 8b/10b during reset.
07-12-2016 05:35 AM
07-12-2016 07:29 AM
Yes. The self_test throw an error.
The self_test read reg 0x200 and got 0x200003. Other regs are all correct.
So I checked the PG064 and found the reg may be 0x200003 instead of 0x03, if bit 21 is '1' by default.
I think it may be a bug of self_test example.
07-12-2016 11:24 PM