linux-kernel - Re: [PATCH v1 2/7] dt-bindings: usb: hpe,gxp-udc: Add binding for gxp gadget

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Message-ID: <03251423-b136-e4ff-2485-bbb16c0c7f5b@linaro.org>
Date:   Fri, 4 Nov 2022 16:09:49 -0400
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     "Yu, Richard" <richard.yu@....com>,
        "Verdun, Jean-Marie" <verdun@....com>,
        "Hawkins, Nick" <nick.hawkins@....com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "linux@...linux.org.uk" <linux@...linux.org.uk>,
        "balbi@...nel.org" <balbi@...nel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "Chang, Clay" <clayc@....com>
Subject: Re: [PATCH v1 2/7] dt-bindings: usb: hpe,gxp-udc: Add binding for gxp
 gadget

On 04/11/2022 16:03, Yu, Richard wrote:
> Hi Mr. Kozlowski,
> 
> Thank you very much for your quick review and feedbacks.
> 
> I will modify the patches based on your feedback accordingly.
> 
> On this specific patch, you have questions on how we defined the device/gadget configurations: vdevnum and fepnum.
> 
> Please see my answers following the questions:
> 
>> +  vdevnum:
>> +    description:
>> +      virtual device number.
> 
> That's unusual property... Why numbering devices is part of DT (hardware description)?
> 
>>> Richard: In HPE GXP virtual EHCI controller chipset, it can support up to 8 virtual devices(gadgets). Each device/gadget will be represented by a bit in 8 bits register. For example, the interrupt register bit 0 indicates the interrupt from device 0, bit 1 for device 1 ... so on.  When an user defines a device/gadget, he/she can define the device number as between 0 and 7. Thus, the driver can up to the bit position. That is why we have numbering devices as port of DT.
> 
>> +
>> +  fepnum:
>> +    description:
>> +      number of the flexible end-points this device is needed.
> 
> Similar question.
> 
>>> Richard: In HPE GXP virtual EHCI Controller chipset, there is a flexible EP pool. Each flexible EP has its own mapping register. The mapping register bit 0 to 3 is for device number (vdevnum) and bit 4 to 7 is for EP number inside the device. The device driver configures the mapping register to assign a flexible EP to a specific device.  Here, "fepnum" is the input letting the driver know how many EP is needed for this device/gadget.
> 
> Hope I have answered your questions on "vdevnum" and "fepnum". 

Unfortunately I don't see your answers... Or actually I am not sure what
is the answer and what is not. What is unusual, you did not quote my
email but quoted something else. Please send it again, but following
normal mailing list netiquette for replies.

Here is one:

https://en.opensuse.org/openSUSE:Mailing_list_netiquette

Just don't use corporate style of emails on mailing list. We usually
cannot handle them...

Best regards,
Krzysztof