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From: Stephen Boyd <swboyd@chromium.org>
To: Sankeerth Billakanti <quic_sbillaka@quicinc.com>,
	devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org,
	freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: robdclark@gmail.com, seanpaul@chromium.org,
	quic_kalyant@quicinc.com, quic_abhinavk@quicinc.com,
	dianders@chromium.org, quic_khsieh@quicinc.com,
	bjorn.andersson@linaro.org, sean@poorly.run, airlied@linux.ie,
	daniel@ffwll.ch, dmitry.baryshkov@linaro.org,
	quic_vproddut@quicinc.com, quic_aravindh@quicinc.com,
	steev@kali.org
Subject: Re: [PATCH v9 3/4] drm/msm/dp: wait for hpd high before aux transaction
Date: Fri, 22 Apr 2022 18:38:46 -0700	[thread overview]
Message-ID: <CAE-0n520s1XdUO5k2xxX16AsJc8pCjV8yXeR-0f5BC7A5+f-Vw@mail.gmail.com> (raw)
In-Reply-To: <1650618666-15342-4-git-send-email-quic_sbillaka@quicinc.com>

Quoting Sankeerth Billakanti (2022-04-22 02:11:05)
> The source device should ensure the sink is ready before proceeding to
> read the sink capability or perform any aux transactions. The sink
> will indicate its readiness by asserting the HPD line. The controller
> driver needs to wait for the hpd line to be asserted by the sink before
> it performs any aux transactions.
>
> The eDP sink is assumed to be always connected. It needs power from the
> source and its HPD line will be asserted only after the panel is powered
> on. The panel power will be enabled from the panel-edp driver and only
> after that, the hpd line will be asserted.
>
> Whereas for DP, the sink can be hotplugged and unplugged anytime. The hpd
> line gets asserted to indicate the sink is connected and ready. Hence
> there is no need to wait for the hpd line to be asserted for a DP sink.
>
> Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com>
> Reviewed-by: Douglas Anderson <dianders@chromium.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@chromium.org>

WARNING: multiple messages have this Message-ID (diff)
From: Stephen Boyd <swboyd@chromium.org>
To: Sankeerth Billakanti <quic_sbillaka@quicinc.com>,
	devicetree@vger.kernel.org,  dri-devel@lists.freedesktop.org,
	freedreno@lists.freedesktop.org,  linux-arm-msm@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: quic_kalyant@quicinc.com, dianders@chromium.org,
	quic_vproddut@quicinc.com, airlied@linux.ie,
	quic_abhinavk@quicinc.com, steev@kali.org,
	quic_khsieh@quicinc.com, seanpaul@chromium.org,
	dmitry.baryshkov@linaro.org, quic_aravindh@quicinc.com,
	bjorn.andersson@linaro.org, sean@poorly.run
Subject: Re: [PATCH v9 3/4] drm/msm/dp: wait for hpd high before aux transaction
Date: Fri, 22 Apr 2022 18:38:46 -0700	[thread overview]
Message-ID: <CAE-0n520s1XdUO5k2xxX16AsJc8pCjV8yXeR-0f5BC7A5+f-Vw@mail.gmail.com> (raw)
In-Reply-To: <1650618666-15342-4-git-send-email-quic_sbillaka@quicinc.com>

Quoting Sankeerth Billakanti (2022-04-22 02:11:05)
> The source device should ensure the sink is ready before proceeding to
> read the sink capability or perform any aux transactions. The sink
> will indicate its readiness by asserting the HPD line. The controller
> driver needs to wait for the hpd line to be asserted by the sink before
> it performs any aux transactions.
>
> The eDP sink is assumed to be always connected. It needs power from the
> source and its HPD line will be asserted only after the panel is powered
> on. The panel power will be enabled from the panel-edp driver and only
> after that, the hpd line will be asserted.
>
> Whereas for DP, the sink can be hotplugged and unplugged anytime. The hpd
> line gets asserted to indicate the sink is connected and ready. Hence
> there is no need to wait for the hpd line to be asserted for a DP sink.
>
> Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com>
> Reviewed-by: Douglas Anderson <dianders@chromium.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@chromium.org>

  reply	other threads:[~2022-04-23  1:38 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-22  9:11 [PATCH v9 0/4] Add support for the eDP panel over aux_bus Sankeerth Billakanti
2022-04-22  9:11 ` Sankeerth Billakanti
2022-04-22  9:11 ` [PATCH v9 1/4] drm/msm/dp: Add eDP support via aux_bus Sankeerth Billakanti
2022-04-22  9:11   ` Sankeerth Billakanti
2022-04-22 14:03   ` Doug Anderson
2022-04-22 14:03     ` Doug Anderson
2022-04-23  0:13   ` Stephen Boyd
2022-04-23  0:13     ` Stephen Boyd
2022-04-25  9:39     ` Sankeerth Billakanti (QUIC)
2022-04-25  9:39       ` Sankeerth Billakanti (QUIC)
2022-04-25 20:26       ` Stephen Boyd
2022-04-25 20:26         ` Stephen Boyd
2022-04-25 21:12         ` Dmitry Baryshkov
2022-04-25 21:12           ` Dmitry Baryshkov
2022-04-26  1:58           ` Sankeerth Billakanti (QUIC)
2022-04-26  1:58             ` Sankeerth Billakanti (QUIC)
2022-04-22  9:11 ` [PATCH v9 2/4] drm/msm/dp: Support only IRQ_HPD and REPLUG interrupts for eDP Sankeerth Billakanti
2022-04-22  9:11   ` Sankeerth Billakanti
2022-04-22 14:03   ` Doug Anderson
2022-04-22 14:03     ` Doug Anderson
2022-04-22 15:55   ` Doug Anderson
2022-04-22 15:55     ` Doug Anderson
2022-04-22 16:04     ` Abhinav Kumar
2022-04-22 16:04       ` Abhinav Kumar
2022-04-22 16:10       ` Doug Anderson
2022-04-22 16:10         ` Doug Anderson
2022-04-22 17:35         ` Abhinav Kumar
2022-04-22 17:35           ` Abhinav Kumar
2022-04-23  0:29   ` Stephen Boyd
2022-04-23  0:29     ` Stephen Boyd
2022-04-25  2:55     ` Sankeerth Billakanti (QUIC)
2022-04-25  2:55       ` Sankeerth Billakanti (QUIC)
2022-04-25 20:27       ` Stephen Boyd
2022-04-25 20:27         ` Stephen Boyd
2022-04-26  3:45         ` Sankeerth Billakanti (QUIC)
2022-04-26  3:45           ` Sankeerth Billakanti (QUIC)
2022-04-22  9:11 ` [PATCH v9 3/4] drm/msm/dp: wait for hpd high before aux transaction Sankeerth Billakanti
2022-04-22  9:11   ` Sankeerth Billakanti
2022-04-23  1:38   ` Stephen Boyd [this message]
2022-04-23  1:38     ` Stephen Boyd
2022-04-22  9:11 ` [PATCH v9 4/4] drm/msm/dp: Support the eDP modes given by panel Sankeerth Billakanti
2022-04-22  9:11   ` Sankeerth Billakanti
2022-04-23  1:39   ` Stephen Boyd
2022-04-23  1:39     ` Stephen Boyd

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