linux-kernel - Re: [PATCH v9 10/17] phy: Add driver for rockchip Display Port PHY

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Message-ID: <20151104011348.GL7274@google.com>
Date:	Tue, 3 Nov 2015 17:13:48 -0800
From:	Brian Norris <computersforpeace@...il.com>
To:	Yakir Yang <ykk@...k-chips.com>
Cc:	Inki Dae <inki.dae@...sung.com>,
	Andrzej Hajda <a.hajda@...sung.com>,
	Joonyoung Shim <jy0922.shim@...sung.com>,
	Seung-Woo Kim <sw0312.kim@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Jingoo Han <jingoohan1@...il.com>,
	Thierry Reding <treding@...dia.com>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Rob Herring <robh+dt@...nel.org>,
	Heiko Stuebner <heiko@...ech.de>,
	Mark Yao <mark.yao@...k-chips.com>, djkurtz@...omium.org,
	dianders@...omium.org,
	Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
	linux-samsung-soc@...r.kernel.org,
	Russell King <linux@....linux.org.uk>,
	linux-rockchip@...ts.infradead.org,
	Kishon Vijay Abraham I <kishon@...com>,
	javier@....samsung.com, Kukjin Kim <kgene@...nel.org>,
	robherring2@...il.com, devicetree@...r.kernel.org,
	Pawel Moll <pawel.moll@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Sean Paul <seanpaul@...omium.org>,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org, emil.l.velikov@...il.com,
	linux-kernel@...r.kernel.org, Kumar Gala <galak@...eaurora.org>,
	ajaynumb@...il.com, Andy Yan <andy.yan@...k-chips.com>
Subject: Re: [PATCH v9 10/17] phy: Add driver for rockchip Display Port PHY

Hi Yakir,

On Wed, Nov 04, 2015 at 08:48:38AM +0800, Yakir Yang wrote:
> On 11/03/2015 12:38 PM, Brian Norris wrote:
> >On Thu, Oct 29, 2015 at 09:58:38AM +0800, Yakir Yang wrote:
> >(FYI, I came across this by inspection when comparing Heiko's
> >'somewhat-stable' branch [1] with this series. The former brings up eDP
> >fine on veyron-jaq, whereas this one doesn't yet, even with the above
> >change. Still debugging the issue.)
> 
> Hmm... I'm not sure whether your eDP screen have the hotplug signal, so I

I believe hotplug is hooked up but...

> think you can try to add "analogix,force-hpd" flag into
> rk3288-veyron-jaq.dts
> 
> &edp {
>     analogix,need-force-hpd;
> }

...already tried, just in case. No luck.

> If that changes couldn't fix the problem, guess you may need max the panel
> power up delay time which pointed by Heiko. Like:
> 
> Thanks,
> - Yakir
> 
> 
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index 4fa5f69..546a506 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -82,6 +82,13 @@ static int analogix_dp_detect_hpd(struct
> analogix_dp_device *dp)
>          */
>         dev_dbg(dp->dev, "failed to get hpd plug status, try to
> force hpd\n");
> 
> +       /*
> +        * Hotplug signal would indicate the right time to operate
> +        * panel after poweron, but if the hotplug is missing, then
> +        * panel would need wait hundreds of milliseconds at here.
> +        */
> +       mdelay(100);
> +
>         analogix_dp_force_hpd(dp);
> 
>         if (analogix_dp_get_plug_in_status(dp) != 0) {

I'll give that a try. Per Heiko's suggestion, I've already hacked around
with adding delays in the regulator node, but this could give slightly
different behavior. I doubt it'll help, but I'll let you know if it
does.

Regards,
Brian
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