linux-kernel - Re: [PATCH 00/49] DRM driver for Hikey 970

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Message-ID: <20200825202153.GA237836@ravnborg.org>
Date:   Tue, 25 Aug 2020 22:21:53 +0200
From:   Sam Ravnborg <sam@...nborg.org>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Xinliang Liu <xinliang.liu@...aro.org>,
        Wanchun Zheng <zhengwanchun@...ilicon.com>,
        linuxarm@...wei.com, dri-devel <dri-devel@...ts.freedesktop.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        devel@...verdev.osuosl.org, Daniel Borkmann <daniel@...earbox.net>,
        John Fastabend <john.fastabend@...il.com>,
        Xiubin Zhang <zhangxiubin1@...wei.com>,
        Wei Xu <xuwei5@...ilicon.com>, David Airlie <airlied@...ux.ie>,
        Xinwei Kong <kong.kongxinwei@...ilicon.com>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Bogdan Togorean <bogdan.togorean@...log.com>,
        Laurentiu Palcu <laurentiu.palcu@....com>,
        linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        Liwei Cai <cailiwei@...ilicon.com>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Chen Feng <puck.chen@...ilicon.com>,
        Alexei Starovoitov <ast@...nel.org>,
        linaro-mm-sig@...ts.linaro.org, Rob Herring <robh+dt@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>, mauro.chehab@...wei.com,
        Rob Clark <robdclark@...omium.org>,
        linux-arm-kernel@...ts.infradead.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Liuyao An <anliuyao@...wei.com>,
        Rongrong Zou <zourongrong@...il.com>, bpf@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH 00/49] DRM driver for Hikey 970

Hi Mauro.

Laurent and I discussed this driver a little on irc.
Some highlights:

This parts could use register names:
+       writel(0x2, noc_dss_base + 0xc);
+       writel(0x2, noc_dss_base + 0x8c);
+       writel(0x2, noc_dss_base + 0x10c);
+       writel(0x2, noc_dss_base + 0x18c);

The two nodes in the DT for DPE and DSI uses overlapping range for reg
entries. It looks like a syscon node or some iommu thing is needed to do
this properly.

The chain will lok like this:

DPE -> DSI -> video mux -> {adv7533, panel}

But drm_bridge has not yet support for such non-linear setup.
The recommendation is to focus on the HDMI prat. Then we can later
come up with support for a video mux.

The video mux should have a dedicated node with one input node and two
output nodes. Which is also where the gpio should be.

The DSI node references two DPHY instances - should it be PHY driver(s)?

Does the DSI part contain one or two instances. Clocks looks duplicated.

Does the DPE and DSI share a lot of register blocks - or does it just
look like this from a first point of view?

You can read though the logs here:
https://people.freedesktop.org/~cbrill/dri-log/index.php

Could you please try to get back on some of the points above so we can
help you move forward in the right direction.

Thanks,
	Sam