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Message-ID: <aeeb0dfb-87e2-4024-9d4a-0b9529477315@linaro.org>
Date: Mon, 15 Jan 2024 21:43:21 +0100
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Subject: Re: [PATCH 2/3] ASoC: dt-bindings: xmos,xvf3500: add bindings for
 XMOS XVF3500
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To: Javier Carrasco <javier.carrasco@wolfvision.net>,
 Rob Herring <robh+dt@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>, Liam Girdwood <lgirdwood@gmail.com>,
 Mark Brown <broonie@kernel.org>, Jaroslav Kysela <perex@perex.cz>,
 Takashi Iwai <tiwai@suse.com>
Cc: Rob Herring <robh@kernel.org>, devicetree@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-sound@vger.kernel.org,
 linux-usb@vger.kernel.org
References: <20240115-feature-xvf3500_driver-v1-0-ed9cfb48bb85@wolfvision.net>
 <20240115-feature-xvf3500_driver-v1-2-ed9cfb48bb85@wolfvision.net>
 <333c2986-c7c2-4a46-90cf-b59ae206e55a@linaro.org>
 <96abddcc-fa65-4f27-84fe-2281fe0fcf1c@wolfvision.net>
 <644f7f02-405d-47fb-bc72-4d54e897255f@linaro.org>
 <5db4b898-93d5-446f-bfed-b57847f9967a@wolfvision.net>
 <435f502c-1e1b-4d40-8dcc-34487905d69c@linaro.org>
 <b7f76546-9998-43e0-abff-a4e73817dbae@wolfvision.net>
 <47bdc31c-50d2-4d33-9339-5132b6364539@linaro.org>
 <16027339-0a82-4dd1-86aa-19fda6e23f88@wolfvision.net>
From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
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In-Reply-To: <16027339-0a82-4dd1-86aa-19fda6e23f88@wolfvision.net>
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On 15/01/2024 20:43, Javier Carrasco wrote:
> On 15.01.24 19:11, Krzysztof Kozlowski wrote:
>> On 15/01/2024 17:24, Javier Carrasco wrote:
>>> Do you mean that the XVF3500 should not be represented as a platform
>>> device and instead it should turn into an USB device represented as a
>>> node of an USB controller? Something like this (Rockchip SoC):
>>>
>>> &usb_host1_xhci {
>>> 	...
>>>
>>> 	xvf3500 {
>>> 		...
>>> 	};
>>> };
>>>
>>> Did I get you right or is that not the correct representation? Thank you
>>> again.
>>
>> I believe it should be just like onboard hub. I don't understand why
>> onboard hub was limited to hub, because other USB devices also could be
>> designed similarly by hardware folks :/
>>
>> And if we talk about Linux drivers, then your current solution does not
>> support suspend/resume and device unbind.
>>
>> Best regards,
>> Krzysztof
>>
> 
> Actually this series is an attempt to get rid of a misuse of the
> onboard_usb_hub driver by a device that is not a HUB, but requires the
> platform-part of that driver for the initialization.

That's just naming issue, isn't it?

> 
> What would be the best approach to provide support upstream? Should I
> turn this driver into a generic USB driver that does what the
> platform-part of the onboard HUB does? Or are we willing to accept

No, because you did not solve the problems I mentioned. This is neither
accurate hardware description nor proper Linux driver model handling PM
and unbind.

> non-HUB devices in the onboard_usb_hub driver even though it supports
> more operations?
> 
> I am adding linux-usb to this thread in case someone has other suggestions.

I don't see any difference between this device and onboard hub. The
concept and the problem is the same. Therefore either treat it as as
onboard hub or come with USB-version of PCI power sequencing.

https://lore.kernel.org/all/20240104130123.37115-1-brgl@bgdev.pl/

Best regards,
Krzysztof