Hi Thierry & Rob,
在 2015/8/25 21:27, Rob Herring 写道:
On Tue, Aug 25, 2015 at 4:15 AM, Thierry Reding treding@nvidia.com wrote:
On Sun, Aug 23, 2015 at 06:23:14PM -0500, Rob Herring wrote:
On Wed, Aug 19, 2015 at 9:50 AM, Yakir Yang ykk@rock-chips.com wrote:
[...]
-analogix,link-rate:max link rate supported by the eDP controller.LINK_RATE_1_62GBPS = 0x6, LINK_RATE_2_70GBPS = 0x0A,LINK_RATE_5_40GBPS = 0x14Same here. I'd rather see something like "link-rate-mbps" and use the actual rate.
There is no need whatsoever to hard-code this in DT. (e)DP provides the means to detect what rate the link supports and the specification provides guidance on how to select an appropriate one.
Good, even better.
I do think we still need keep this DT prop yet.
I think drm_dp_help.c could get the "panel" max link-rate and lane-count, but it's not enough, we still need knew the "eDP controller" max link-rate and lane-count.
Let me show the exact example that happened in my side. When I connect my board to my 2K DP-1.2 TV. Analogix dp driver would get the max link-rate from dpcd, and the max link-rate is 5.4Gbps. So if I just set eDP controller link-rate to 5.4Gbps, the DP TV just broken, do not light up normally.
This reason why TV broken is the max link-rate which support by RK3288 eDP controller is 2.7Gbps. Here are the exact words that RK3288 eDP TRM said:
*Compliant with DisplayPortTM Specification, Version 1.2. Compliant with eDPTM Specification, Version 1.3. HDCP v1.3 amendment for DisplayPortTM Revision 1.0. Main link containing 4 physical lanes of 2.7/1.62 Gbps/lane * **
Beside I haven't found there are some registers would indicate the eDP controller max link-rate and lane-count, so this is why I still instance that we need this DT prop to indicata "Max rate controller support".
So, I wish you could agree with me on this point.
Thanks, - Yakir
Rob