Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20201020115959.2658-1-Sergey.Semin@baikalelectronics.ru> <20201020115959.2658-30-Sergey.Semin@baikalelectronics.ru>
In-Reply-To: <20201020115959.2658-30-Sergey.Semin@baikalelectronics.ru>
From:   John Stultz <john.stultz@linaro.org>
Date:   Tue, 13 Jul 2021 17:07:00 -0700
Message-ID: <CALAqxLX_FNvFndEDWtGbFPjSzuAbfqxQE07diBJFZtftwEJX5A@mail.gmail.com>
Subject: Re: [PATCH 29/29] arm64: dts: qcom: Harmonize DWC USB3 DT nodes name
To:     Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc:     Felipe Balbi <balbi@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        Linux USB List <linux-usb@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Serge Semin <fancer.lancer@gmail.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Amit Pundir <amit.pundir@linaro.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, Oct 20, 2020 at 5:10 AM Serge Semin
<Sergey.Semin@baikalelectronics.ru> wrote:
>
> In accordance with the DWC USB3 bindings the corresponding node
> name is suppose to comply with the Generic USB HCD DT schema, which
> requires the USB nodes to have the name acceptable by the regexp:
> "^usb(@.*)?" . Make sure the "snps,dwc3"-compatible nodes are correctly
> named.
>
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>

I know folks like to ignore this, but this patch breaks AOSP on db845c. :(

In the exact same way an earlier patch broke HiKey960:
  https://lore.kernel.org/lkml/CALAqxLWGujgR7p8Vb5S_RimRVYxwm5XF-c4NkKgMH-43wEBaWg@mail.gmail.com/

(which I still have to carry a revert for).

I get that this change is useful so more dynamic userland can find
devices using consistent naming with future kernels (but doesn't the
dynamic userland have to handle the case for older kernels as well?)
But for userland that uses static configs, its painful as updating
userland to use the new node ids then causes older kernels to fail.

I'm looking into how we might be able to probe and set the property
dynamically, but AOSP's init system is far more aligned to static
configs.

This will probably be ignored again, but it would be nice if we could
have a release where DTS changes don't break userland for one of my
boards. As it feels like its been awhile.

thanks
-john