From: Krzysztof Kozlowski <krzk@kernel.org>
To: Aswath Govindraju <a-govindraju@ti.com>,
Rob Herring <robh+dt@kernel.org>
Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
linux-usb@vger.kernel.org, Felipe Balbi <balbi@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Roger Quadros <rogerq@kernel.org>,
Vignesh Raghavendra <vigneshr@ti.com>,
Kishon Vijay Abraham I <kishon@ti.com>
Subject: Re: [PATCH v2 1/2] dt-bindings: usb: Add documentation for AM62 USB Wrapper module
Date: Thu, 24 Mar 2022 12:53:08 +0100 [thread overview]
Message-ID: <2b33798e-23c2-d4a5-171a-55c28bc40c40@kernel.org> (raw)
In-Reply-To: <41f79aa5-1e04-53f8-ab21-85fe6039e24e@ti.com>
On 24/03/2022 12:40, Aswath Govindraju wrote:
> Hi Krzysztof,
>
> On 24/03/22 16:37, Krzysztof Kozlowski wrote:
>> On 24/03/2022 08:34, Aswath Govindraju wrote:
>>> Add bindings for the TI's AM62 wrapper module for the Synopsys USBSS-DRD
>>> controller.
>>>
>>> Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
>>> ---
>>>
>>> Changes since v1:
>>> - made correction in grammer of clocks property description
>>> and added maxItems in the interrupts property based on comments
>>> received from Roger
>>> - corrected the title, fixed the description of
>>> ti,syscon-phy-pll-refclk, added pattern properties and child node
>>> in the example based on the comments from Krzysztof.
>>>
>>> .../devicetree/bindings/usb/ti,am62-usb.yaml | 117 ++++++++++++++++++
>>> 1 file changed, 117 insertions(+)
>>> create mode 100644 Documentation/devicetree/bindings/usb/ti,am62-usb.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/usb/ti,am62-usb.yaml b/Documentation/devicetree/bindings/usb/ti,am62-usb.yaml
>>> new file mode 100644
>>> index 000000000000..452bfdc6fb09
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/usb/ti,am62-usb.yaml
>>> @@ -0,0 +1,117 @@
>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/usb/ti,am62-usb.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: TI's AM62 wrapper module for the Synopsys USBSS-DRD controller
>>> +
>>> +maintainers:
>>> + - Aswath Govindraju <a-govindraju@ti.com>
>>> +
>>> +properties:
>>> + compatible:
>>> + const: ti,am62-usb
>>> +
>>> + reg:
>>> + maxItems: 1
>>> +
>>> + ranges: true
>>> +
>>> + power-domains:
>>> + description:
>>> + PM domain provider node and an args specifier containing
>>> + the USB ISO device id value. See,
>>> + Documentation/devicetree/bindings/soc/ti/sci-pm-domain.yaml
>>> + maxItems: 1
>>> +
>>> + clocks:
>>> + description: Clock phandle to usb2_refclk
>>> + maxItems: 1
>>> +
>>> + clock-names:
>>> + items:
>>> + - const: ref
>>> +
>>> + id-gpio:
>>> + description:
>>> + GPIO to be used as ID pin
>>> + maxItems: 1
>>
>> I have doubts about this. If you USB controller handles the ID pin, then
>> probably this should be moved to usb-connector.yaml. I did not see
>> id-gpio in any other USB controller blocks.
>>
>
> Yes, the USB wrapper handles the ID pin operation only. It also reads
> the status of VBUS by reading a register from its MMR and not using a
> gpio. After evaluating the role the based on the states if id pin and
> VBUS, this role is communicated to the dwc3 core driver using extcon.
> There is no way for the dwc3 driver to detect the role on its own.
>
>
> The usb-connector(drivers/usb/common/usb-conn-gpio.c) driver, seems to
> be implemented for driving the VBUS, based on ID and VBUS pin status.
> However, in case of the above implementation we need to communicate the
> detected role to the dwc3 core driver. Also, the wrapper does not
> control VBUS but it is the dwc3 core driver that drives the VBUS.
> Therefore, I think the usb-connector implementation cannot be used here.
I don't think about usb-conn-gpio.c but using the binding generic
binding for usb-X-connector and define a connector with ID.
Actually Rob could help here.
Rob,
Should the id-gpio be modeled as a property in this glue/wrapper driver
or rather as part of usb-connector child node?
Best regards,
Krzysztof
next prev parent reply other threads:[~2022-03-24 11:53 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-24 7:34 [PATCH v2 0/2] AM62: Add support for AM62 USB wrapper driver Aswath Govindraju
2022-03-24 7:34 ` [PATCH v2 1/2] dt-bindings: usb: Add documentation for AM62 USB Wrapper module Aswath Govindraju
2022-03-24 11:07 ` Krzysztof Kozlowski
2022-03-24 11:40 ` Aswath Govindraju
2022-03-24 11:53 ` Krzysztof Kozlowski [this message]
2022-04-01 0:20 ` Rob Herring
2022-04-01 5:04 ` Aswath Govindraju
2022-04-01 7:49 ` Krzysztof Kozlowski
2022-04-01 8:05 ` Aswath Govindraju
2022-03-24 7:34 ` [PATCH v2 2/2] drivers: usb: dwc3: Add AM62 USB wrapper driver Aswath Govindraju
2022-04-07 5:32 ` [PATCH v2 0/2] AM62: Add support for " Aswath Govindraju
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