linux-kernel - Re: [PATCH v8 0/3] drm: Add support for Cadence MHDP DPI/DP bridge and J721E wrapper.

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Message-ID: <20200825073219.GA5528@bogon.m.sigxcpu.org>
Date:   Tue, 25 Aug 2020 09:32:19 +0200
From:   Guido Günther <agx@...xcpu.org>
To:     Swapnil Kashinath Jakhade <sjakhade@...ence.com>
Cc:     Tomi Valkeinen <tomi.valkeinen@...com>,
        "airlied@...ux.ie" <airlied@...ux.ie>,
        "daniel@...ll.ch" <daniel@...ll.ch>,
        "Laurent.pinchart@...asonboard.com" 
        <Laurent.pinchart@...asonboard.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "a.hajda@...sung.com" <a.hajda@...sung.com>,
        "narmstrong@...libre.com" <narmstrong@...libre.com>,
        "jonas@...boo.se" <jonas@...boo.se>,
        "jernej.skrabec@...l.net" <jernej.skrabec@...l.net>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Milind Parab <mparab@...ence.com>,
        Yuti Suresh Amonkar <yamonkar@...ence.com>,
        "praneeth@...com" <praneeth@...com>,
        "nsekhar@...com" <nsekhar@...com>, "jsarha@...com" <jsarha@...com>,
        "sandor.yu@....com" <sandor.yu@....com>
Subject: Re: [PATCH v8 0/3] drm: Add support for Cadence MHDP DPI/DP bridge
 and J721E wrapper.

Hi Swapnil,
On Mon, Aug 24, 2020 at 07:16:31AM +0000, Swapnil Kashinath Jakhade wrote:
[..snip..]
> Following are the differences between MHDP IPs from Cadence for Rockchip, TI and NxP:
> 
> The Rockchip and NXP MHDP Core shares the same part (IP8501) which is DP v1.3 SST
> Controller with HDCP 2.2/1.x. NXP's version additionally supports HDMI.
> TI uses a different part (IP8546A), which is DP v1.4 with HDCP 2.2/1.x.
> TI DP Controller adds support for additional features such as Multi Stream Support (MST),
> Forward Error Correction (FEC) and Compression (DSC).
> 
> Also, FW used for TI has significant differences than FW used for Rockchip or NXP.
> NxP and TI firmware are developed and maintained separately by Cadence and are in
> active support.
> 
> From the Linux driver perspective, given the differences, it would make sense to have
> TI driver maintained separately.

Thanks for the clarification, that indeed helps a lot. So the rockchip
and nxp drivers can be merged while the ti one should stay separate.
Cheers,
 -- Guido

> 
> Thanks,
> Swapnil
> 
> > 
> > > I'm worried that if there are IP differences, even if not great ones,
> > > and if the FWs are different and developed separately, it'll be a
> > > constant "fix X for SoC A, and accidentally break Y for SoC B and C",
> > especially if too much code is shared.
> > >
> > > In the long run I'm all for a single driver (or large shared parts),
> > > but I'm not sure if we should start with that approach.
> > 
> > 
> > 
> > 
> > >
> > >  Tomi
> > >
> > > --
> > > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> > > Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
> > >
>