Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <5c7a1763-01fb-249d-a301-9164e2139ac6@linaro.org>
Date:   Sun, 19 Jun 2022 13:49:04 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.10.0
Subject: Re: [PATCH 2/3] dt-bindings: usb: mtk-xhci: Allow middle optional
 clocks to be missing
Content-Language: en-US
To:     Chunfeng Yun <chunfeng.yun@mediatek.com>,
        =?UTF-8?B?TsOtY29sYXMgRi4gUi4gQS4gUHJhZG8=?= 
        <nfraprado@collabora.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Matthias Brugger <matthias.bgg@gmail.com>
Cc:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>, kernel@collabora.com,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Rob Herring <robh+dt@kernel.org>, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-mediatek@lists.infradead.org, linux-usb@vger.kernel.org
References: <20220617222916.2435618-1-nfraprado@collabora.com>
 <20220617222916.2435618-3-nfraprado@collabora.com>
 <d95e046262751a7f746fabc5f1d9a39e675730b3.camel@mediatek.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <d95e046262751a7f746fabc5f1d9a39e675730b3.camel@mediatek.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

On 19/06/2022 09:40, Chunfeng Yun wrote:
> On Fri, 2022-06-17 at 18:29 -0400, Nícolas F. R. A. Prado wrote:
>> The current clock list in the binding doesn't allow for one of the
>> optional clocks to be missing and a subsequent clock to be present.
>> An
>> example where this is an issue is in mt8192.dtsi, which has "sys_ck",
>> "ref_ck", "xhci_ck" and would cause dtbs_check warnings.
> How about using fixed clock instead to fix the check warning?
> Using enum way seems make it more complex.
> 

That would mean the clock is not actually optional. The DTS should
reflect the hardware so either you have the clock there or not. Either
it is an input or not. Of course there are some exceptions (like
non-controllable clock or regulator which not always has to be modeled).

Best regards,
Krzysztof