linux-kernel - Re: [PATCH] drm: bridge: synopsys/dw-hdmi: Provide default configuration function for HDMI 2.0 PHY

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Date:   Sat, 10 Jun 2017 11:50:07 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Jose Abreu <Jose.Abreu@...opsys.com>
Cc:     Mark Yao <mark.yao@...k-chips.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Archit Taneja <architt@...eaurora.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Carlos Palminha <CARLOS.PALMINHA@...opsys.com>
Subject: Re: [PATCH] drm: bridge: synopsys/dw-hdmi: Provide default configuration function for HDMI 2.0 PHY

Hi Jose,

On Friday 09 Jun 2017 13:53:12 Jose Abreu wrote:
> On 09-06-2017 12:04, Jose Abreu wrote:
> > Currently HDMI 2.0 PHYs do not have a default configuration function.
> > 
> > As these PHYs have the same register layout as the 3D PHYs we can
> > safely use the default configuration function.
> 
> I may have been a little to fast arriving at this conclusion. I
> mean most of the registers match but in the configuration
> function there are registers that do not match. Did you actually
> test this configuration function with an HDMI 2.0 phy? And did
> you test with different video modes? From my experience the phy
> may be wrongly configured and sometimes work anyway.
> 
> Do please retest with as many video modes as you can and give me
> your phy ID (read from controller config reg HDMI_CONFIG2_ID).

The Renesas R-Car Gen3 HDMI PHY reports an DWC HDMI 2.0 TX PHY ID, but has a 
configuration function (rcar_hdmi_phy_configure() in drivers/gpu/drm/rcar-
du/rcar_dw_hdmi.c) that doesn't match hdmi_phy_configure_dwc_hdmi_3d_tx(). 
>From the information I have been given the layout of the configuration 
registers haven't been changed by Renesas. I know we've briefly discussed this 
in the past, but I'd appreciate if you could have a second look and tell me 
what you think.

> >  If, for some reason,
> > 
> > the PHY is custom this change will not make any impact because
> > in configuration function we prefer the pdata provided configuration
> > function over the internal one.
> > 
> > This patch is based on today's drm-misc-next branch.
> > 
> > Signed-off-by: Jose Abreu <joabreu@...opsys.com>
> > Cc: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> > Cc: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
> > Cc: Archit Taneja <architt@...eaurora.org>
> > Cc: Andrzej Hajda <a.hajda@...sung.com>
> > Cc: Mark Yao <mark.yao@...k-chips.com>
> > Cc: Carlos Palminha <palminha@...opsys.com>
> > ---
> > 
> >  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c index ead1124..10c8d8c 100644
> > --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > @@ -2170,6 +2170,7 @@ static irqreturn_t dw_hdmi_irq(int irq, void
> > *dev_id)
> >  		.name = "DWC HDMI 2.0 TX PHY",
> >  		.gen = 2,
> >  		.has_svsret = true,
> > +		.configure = hdmi_phy_configure_dwc_hdmi_3d_tx,
> >  	}, {
> >  		.type = DW_HDMI_PHY_VENDOR_PHY,
> >  		.name = "Vendor PHY",

-- 
Regards,

Laurent Pinchart