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Date: Mon, 20 Apr 2020 06:32:27 +0530
From: Kunal Joshi <kunal1.joshi@intel.com>
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 <20200420075512.ehv5w2yiikymql5h@ahiler-desk1.fi.intel.com>
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Subject: Re: [igt-dev] [PATCH i-g-t v2] tests/kms_chamelium: Capture on
 type-c
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To: Arkadiusz Hiler <arkadiusz.hiler@intel.com>, igt-dev@lists.freedesktop.org
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On 2020-04-20 at 10:55:12 +0300, Arkadiusz Hiler wrote:
> On Mon, Apr 20, 2020 at 02:56:13AM +0530, Kunal Joshi wrote:
> > Refreshing the connector everytime and also resetting the
> > state to get HPD reliably.
> 
> Code looks good, but please consider adding a bit more of explanation
> here, something like:
> 
> Chamelium uses HPD pulses to singal the need for a receiver reset using
> DPMS cycle. Some connectors (e.g. DP over TypeC) have limitations and
> will receive just a single such pulse and discard the rest. This lasts
> until we disable the mode completetly and only then reenable it.
> 
> Receiver reset is always required after we set a new mode, so let's
> disable the mode (reset_state() does that) before we switch to a new
> mode. With this we will get the HPD pulses reliably for each iteration
> over all the supoprted modes.
> 
> There are alse targeted test for HPD pulse handling - dp-hpd-*.
>
Yes arek will add this explanation in the commit keeping your rb
Thanks Kunal.
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