Re: [Intel-gfx] ✓ Fi.CI.BAT: success for drm/i915: Enable TPS3/4 on all platforms that support them

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx]  ✓ Fi.CI.BAT: success for drm/i915: Enable TPS3/4 on all platforms that support them
Date: Mon, 22 Mar 2021 17:45:21 +0200	[thread overview]
Message-ID: <YFi7kQldiwmEcc2Y@intel.com> (raw)
In-Reply-To: <161618092043.8631.320174419404607353@emeril.freedesktop.org>

On Fri, Mar 19, 2021 at 07:08:40PM -0000, Patchwork wrote:
> == Series Details ==
> 
> Series: drm/i915: Enable TPS3/4 on all platforms that support them
> URL   : https://patchwork.freedesktop.org/series/88186/
> State : success
> 
> == Summary ==
> 
> CI Bug Log - changes from CI_DRM_9877 -> Patchwork_19815
> ====================================================
> 
> Summary
> -------
> 
>   **SUCCESS**

That's a bit odd considering the link training still fails with this.
Did we convert some erorrs to debugs perhaps, or maybe this never
got flagged as an error?

<7>[    8.235008] i915 0000:00:02.0: [drm:intel_dp_start_link_train [i915]] Using LINK_RATE_SET value 03
<7>[    8.236203] i915 0000:00:02.0: [drm:intel_dp_set_signal_levels [i915]] Using vswing level 0, pre-emphasis level 0, at DPRX
<7>[    8.236341] i915 0000:00:02.0: [drm:intel_dp_program_link_training_pattern [i915]] [ENCODER:307:DDI A/PHY A] Using DP training pattern TPS1
<7>[    8.237373] i915 0000:00:02.0: [drm:intel_dp_link_train_phy [i915]] clock recovery OK
<7>[    8.237460] i915 0000:00:02.0: [drm:intel_dp_program_link_training_pattern [i915]] [ENCODER:307:DDI A/PHY A] Using DP training pattern TPS4
<7>[    8.239054] i915 0000:00:02.0: [drm:intel_dp_dump_link_status.isra.4 [i915]] ln0_1:0x0 ln2_3:0x0 align:0x80 sink:0x0 adj_req0_1:0x0 adj_req2_3:0x0
<7>[    8.239135] i915 0000:00:02.0: [drm:intel_dp_link_train_phy [i915]] Clock recovery check failed, cannot continue channel equalization
<7>[    8.239218] i915 0000:00:02.0: [drm:intel_dp_link_train_phy [i915]] [CONNECTOR:308:eDP-1] Link Training failed at link rate = 270000, lane count = 2, at DPRX

So CR lock is lost as soon as we switch to TPS4. I really wonder if the sink
actually even implements TPS4, and maybe when we write TPS4 to the DPCD reg
it starts to expect some other pattern? Should be semi-easy to confirm
I guess...

One thing I was pondering is whether we're detecting TPS4 vs. TPS3 differently
that eg. Windows. Based on some trawling it looks to me that for some reason
Windows uses the EDP_DPCD_REV>=0x4 check rather than DPCD_REV>=0x14 on eDP
panels when checking for TPS4 suppport. Unfortunately following that
convention here wouldn't help us:

<7>[    6.835706] i915 0000:00:02.0: [drm:intel_dp_init_connector [i915]] eDP DPCD: 04 fb ff
<7>[    8.234921] [drm:drm_dp_read_dpcd_caps] AUX A/DDI A/PHY A: Base DPCD: 14 0a 82 41 00 00 01 c0 02 00 00 00 0f 09 80
<7>[    8.234943] [drm:drm_dp_read_dpcd_caps] AUX A/DDI A/PHY A: DPCD: 14 0a 82 c1 00 00 01 c0 02 00 00 00 0f 09 80

-- 
Ville Syrjälä
Intel
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