Re: [PATCH V3 1/3] dt-bindings: usb: xhci: add support for BCM2711

From: Florian Fainelli <florian.fainelli@broadcom.com>
To: Conor Dooley <conor@kernel.org>, Stefan Wahren <wahrenst@gmx.net>
Cc: Justin Chen <justin.chen@broadcom.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Mathias Nyman <mathias.nyman@intel.com>,
	bcm-kernel-feedback-list@broadcom.com,
	Cyril Brulebois <kibi@debian.org>,
	linux-usb@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH V3 1/3] dt-bindings: usb: xhci: add support for BCM2711
Date: Mon, 4 Dec 2023 09:49:41 -0800	[thread overview]
Message-ID: <0f7fa9f1-2337-428f-8a76-a5b4cac30677@broadcom.com> (raw)
In-Reply-To: <20231204-sevenfold-slashing-bb7ea3419c92@spud>

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On 12/4/23 09:04, Conor Dooley wrote:
> On Sun, Dec 03, 2023 at 05:56:24PM +0100, Stefan Wahren wrote:
>> Hi,
>>
>> Am 03.12.23 um 12:11 schrieb Conor Dooley:
>>> On Sun, Dec 03, 2023 at 11:06:43AM +0000, Conor Dooley wrote:
>>>> On Sun, Dec 03, 2023 at 12:22:15AM +0100, Stefan Wahren wrote:
>>>>> The xHCI IP on the BCM2711 SoC is compatible to "brcm,xhci-brcm-v2",
>>>>> but also requires a power domain.
>>> Hmm
>>> This & the driver change makes it look like your compatible setup should
>>> be `compatible = "brcm,bcm2711-xhci", "brcm,xhci-brcm-v2";.
>> i don't have insight into the hardware, but the fact that the other
>> Broadcom SoC didn't require a power domain before let me think we
>> shouldn't do this. Otherwise this binding was broken before. But Justin
>> and Florian could clarify this.

That seems to me like the right approach, the XHCI controller in 2711 is 
tied to a power domain, however that is not the case for other Broadcom 
STB SoCs.

>>> If the pattern in this patch was repeated, we'd have to modify the
>>> driver like your 2nd patch does for each and new broadcom system that
>>> needs the power domain.
>>  From my understanding the DT compatible should be specific as possible.
> 
> Note that I am suggesting have 2 compatibles. One specific, falling back
> to the existing generic one.

We could do that, yes.
-- 
Florian

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