Quoting Bjorn Andersson (2021-11-05 10:48:37)
On Fri 05 Nov 10:28 PDT 2021, Kuogee Hsieh wrote:
From: Kuogee Hsieh khsieh@codeaurora.org
Combo phy supports both USB and DP simultaneously. There may has a possible conflict during phy initialization phase between USB and DP driver which may cause USB phy timeout when USB tries to power up its phy. This patch has the DP driver not initialize its phy during DP driver initialization phase. Instead DP driver only enable required regulators and clocks so that it is able to receive HPD interrupts after completion of initialization phase. DP driver will initialize its phy when HPD plug-in interrupt received.
Is this a hardware requirement, or is this a issue with the current implementation of the QMP combo phy driver? We should not hack up the DP driver to circumvent the latter.
Also, I don't suppose there's anything here that prevents the HPD to come before the USB PHY is powered up? Even though that seems less likely in practice...
This patch also provides a positive side effects which balance regulator enable count since regulator only enabled at initialize phase and resume and disabled at followed suspend.
Is this something that needs to be fixed separately, so that it can be backported to stable kernels?
Agreed. Please split the regulator balance problem from the DP initialization delay.