On Tue, Aug 25, 2015 at 09:48:01PM +0800, Yakir Yang wrote:
Hi Thierry & Rob,Your driver should know what link rates it supports and restrict itself
å 2015/8/25 21:27, Rob Herring åé:
On Tue, Aug 25, 2015 at 4:15 AM, Thierry Reding <treding@xxxxxxxxxx> wrote:I do think we still need keep this DT prop yet.
On Sun, Aug 23, 2015 at 06:23:14PM -0500, Rob Herring wrote:Good, even better.
On Wed, Aug 19, 2015 at 9:50 AM, Yakir Yang <ykk@xxxxxxxxxxxxxx> wrote:[...]
There is no need whatsoever to hard-code this in DT. (e)DP provides the+ -analogix,link-rate:Same here. I'd rather see something like "link-rate-mbps" and use the
+ max link rate supported by the eDP controller.
+ LINK_RATE_1_62GBPS = 0x6, LINK_RATE_2_70GBPS = 0x0A,
+ LINK_RATE_5_40GBPS = 0x14
means to detect what rate the link supports and the specification
provides guidance on how to select an appropriate one.
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
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
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:
*ïïCompliant with DisplayPortTM Specification, Version 1.2.
ïïCompliant with eDPTM Specification, Version 1.3.
ïïHDCP v1.3 amendment for DisplayPortTM Revision 1.0.
ïïMain 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
max link-rate and lane-count, so this is why I still instance that we need
prop to indicata "Max rate controller support".
So, I wish you could agree with me on this point.
to use those. This is implied by the compatible string and doesn't need
to be duplicated into device tree.