Message-ID: <7c07c822-5962-41d6-b2a9-8ca6bf125b35@linaro.org>
Date: Wed, 21 Feb 2024 09:25:12 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Yang Xiwen <forbidden405@...look.com>, Vinod Koul <vkoul@...nel.org>,
 Kishon Vijay Abraham I <kishon@...nel.org>, Rob Herring
 <robh+dt@...nel.org>, Krzysztof Kozlowski
 <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>,
 Jiancheng Xue <xuejiancheng@...ilicon.com>, Shawn Guo
 <shawn.guo@...aro.org>, Philipp Zabel <p.zabel@...gutronix.de>
Cc: linux-phy@...ts.infradead.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, Kishon Vijay Abraham I <kishon@...com>,
 David Yang <mmyangfl@...il.com>
Subject: Re: [PATCH RFC v3 1/5] dt-bindings: phy: hisi-inno-usb2: convert to
 YAML

On 21/02/2024 09:22, Krzysztof Kozlowski wrote:
> On 20/02/2024 13:12, Yang Xiwen wrote:
>> On 2/20/2024 7:43 PM, Krzysztof Kozlowski wrote:
>>> On 20/02/2024 12:41, Krzysztof Kozlowski wrote:
>>>> On 20/02/2024 11:40, Yang Xiwen wrote:
>>>>> On 2/20/2024 4:16 PM, Krzysztof Kozlowski wrote:
>>>>>> On 19/02/2024 22:49, Yang Xiwen wrote:
>>>>>>> On 2/20/2024 5:37 AM, Krzysztof Kozlowski wrote:
>>>>>>>> On 19/02/2024 22:35, Yang Xiwen wrote:
>>>>>>>>> On 2/20/2024 5:32 AM, Krzysztof Kozlowski wrote:
>>>>>>>>>> On 19/02/2024 22:27, Yang Xiwen via B4 Relay wrote:
>>>>>>>>>>> From: Yang Xiwen <forbidden405@...look.com>
>>>>>>>>>>>
>>>>>>>>>>> Add missing compatible "hisilicon,hi3798mv100-usb2-phy" to compatible
>>>>>>>>>>> list due to prior driver change.
>>>>>>>>>>>
>>>>>>>>>>> Also rename to hisilicon,inno-usb2-phy.yaml and add this name to
>>>>>>>>>>> compatible lists.
>>>>>>>>>>>
>>>>>>>>>>> Fixes: 3940ffc65492 ("phy: hisilicon: Add inno-usb2-phy driver for Hi3798MV100")
>>>>>>>>>>> Signed-off-by: Yang Xiwen <forbidden405@...look.com>
>>>>>>>>>>> ---
>>>>>>>>>>>      .../bindings/phy/hisilicon,inno-usb2-phy.yaml      | 95 ++++++++++++++++++++++
>>>>>>>>>>>      .../devicetree/bindings/phy/phy-hisi-inno-usb2.txt | 71 ----------------
>>>>>>>>>>>      2 files changed, 95 insertions(+), 71 deletions(-)
>>>>>>>>>>>
>>>>>>>>>>> diff --git a/Documentation/devicetree/bindings/phy/hisilicon,inno-usb2-phy.yaml b/Documentation/devicetree/bindings/phy/hisilicon,inno-usb2-phy.yaml
>>>>>>>>>>> new file mode 100644
>>>>>>>>>>> index 000000000000..1b57e0396209
>>>>>>>>>>> --- /dev/null
>>>>>>>>>>> +++ b/Documentation/devicetree/bindings/phy/hisilicon,inno-usb2-phy.yaml
>>>>>>>>>>> @@ -0,0 +1,95 @@
>>>>>>>>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>>>>>>>>> +%YAML 1.2
>>>>>>>>>>> +---
>>>>>>>>>>> +$id: http://devicetree.org/schemas/phy/hisilicon,inno-usb2-phy.yaml#
>>>>>>>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>>>>>>>>> +
>>>>>>>>>>> +title: HiSilicon HiSTB SoCs INNO USB2 PHY device
>>>>>>>>>>> +
>>>>>>>>>>> +maintainers:
>>>>>>>>>>> +  - Yang Xiwen <forbidden405@...look.com>
>>>>>>>>>>> +
>>>>>>>>>>> +properties:
>>>>>>>>>>> +  compatible:
>>>>>>>>>>> +    items:
>>>>>>>>>>> +      - enum:
>>>>>>>>>>> +          - hisilicon,hi3798cv200-usb2-phy
>>>>>>>>>>> +          - hisilicon,hi3798mv100-usb2-phy
>>>>>>>>>>> +      - const: hisilicon,inno-usb2-phy
>>>>>>>>>> According to your driver hisilicon,hi3798mv100-usb2-phy and
>>>>>>>>>> hisilicon,inno-usb2-phy are not compatible.
>>>>>>>>> Ah, i didn't pay too much attention to that. I should remove the entry
>>>>>>>>> for hisilicon,inno-usb2-phy in the driver. Sorry for that.
>>>>>>>> We don't talk here about driver, although I used the driver as proof or
>>>>>>>> argument, because I don't have access to hardware datasheet (and no
>>>>>>>> intention to look there).
>>>>>>>>
>>>>>>>> What I claim is these are not compatible, so respond to this argument,
>>>>>>>> not some other one.
>>>>>>> Why not? Of course they are compatible. All 3 SoCs are using
>>>>>> Why? Because...
>>>>>>
>>>>>>> inno-usb2-phy. The only difference here is the method to access the
>>>>>> ... here! Different programming interface means not compatible.
>>>>>>
>>>>>> Please provide instead any argument that they are compatible, in the
>>>>>> meaning of Devicetree of course. You are claiming inno-usb2-phy  can be
>>>>>> used for hi3798mv100 and it will work fine?
>>>>>>
>>>>>>> registers. They are all enabled by `writing BIT(2) to address 0x6`. In
>>>>>>> the cover letter, I said the driver is actually doing things wrong.
>>>>>> Cover letter does not matter, I don't even read them. Your commits matter.
>>>>>>
>>>>>>> Especially the commit adding PHY_TYPE enums, the name is confusing and
>>>>>>> conveys the wrong info. It's not PHY which are not compatible, it's the
>>>>>>> bus. I'll fix the driver, but still the PHY hardwares are compatible
>>>>>>> between these 3 SoCs.
>>>>>> Provide any argument.
>>>>> Just take a look at the driver. hisi_inno_phy_write_reg() is the
>>>>> function that differs between different models. But for all of them,
>>>>> hisi_inno_phy_setup() is the same.
>>>>>
>>>>>
>>>>> hisi_inno_phy_write_reg() should be moved to a separate bus driver. It's
>>>>> bus-related, not phy. PHY driver should not care how to access the bus,
>>>> So drivers are compatible or hardware? We talk about hardware, not
>>>> drivers...
>>>>
>>>>> but the bus driver should. The PHY driver only needs to use regmap_*
>>>>> APIs to "write BIT(2) to addr 6".
>>>> Different programming interface, so not compatible.
>>> Although maybe I jumped to conclusions too fast. Do you claim that all
>>> registers are the same? All the values, offsets, fields and masks?
>>
>>
>> I don't quite understand. I've said there are two register spaces. One 
>> is the bus to access the PHY (i.e. perictrl for mv100 and cv200 and mmio 
>> for mv200), the other is the PHY register space. So if you are talking 
>> about the prior one, then no, because the PHY is attached to different 
>> buses. But for the latter, yes.
> 
> I am talking about the register address space which the binding document.
> 
>>
>>
>> So here we are talking about two devices. One is the PHY, the other is 
>> the bus the phy attached to.
>>
>>
>> The old binding is mixing all the things up because INNO PHY is the only 
>> device attached to the dedicated bus implemented by perictrl. But it's 
>> not how it works. The binding is for the PHY, not for the bus.
>>
>>
>> For mv100 and cv200, it's: cpu->perictrl->inno-phy. For mv200, it's: 
>> cpu->inno-phy. cpu always accesses peripherals with MMIO, both for 
>> perictrl and mv200-inno-phy. But if the inno-phy is attached to 
>> perictrl. CPU must access the registers of inno-phy through 
>> perictrl(Here perictrl act as a bus driver like a I2C/SPI controller).  
>> For mv100 and cv200, the difference here is only related to to perictrl, 
>> not the PHY itself. For mv200, perictrl does not implement this strange 
>> bus anymore, instead the phy is attached to system bus directly.
> 
> Your driver writes different values depending on the device. For one
> model it writes PHY0_TEST_WREN+PHY0_TEST_RST+PHY0_TEST_CLK. For the
> second PHY1-versions of above.
> 
> The PHY0_TEST_CLK is written to the "reg", so I understand that to the
> device address space.
> 
> If you write two different values to the same register, devices are not
> compatible usually.
> 
>>
>>
>> I don't understand why you say they are not compatible, simply because 
>> they are attached to different buses. For x86, peripherals are mapped in 
> 
> I did not say that. I said that according to quick look in the driver
> and to your explanations you had different programming models and
> interfaces, which means devices are not compatible.
> 
>> dedicated IO address spaces with `IN` and `OUT`, while for ARM, they are 
>> all attached to MMIO buses like APB/AHB/AXI etc.. So peripherals for x86 
>> and peripherals for arm are also not compatible?
> 
> Depends. You did not answer to my question whether you even understand
> what is "compatible", so I assume you don't. Compatible means
> programming models are the same or one is subset of another, so
> effectively both devices work with the same compatible and everything is
> fine.
> 
> Answer yes or not:
> Can PHY1 type of device, so hisilicon,hi3798mv100, bind using
> hisilicon,hi3798mv100-usb2-phy compatible and operate correctly, so you
> remove hisilicon,hi3798mv100-usb2-phy from the driver and device
> operates correctly?

I mixed compatibles, this should be:

Can PHY1 type of device, so hisilicon,hi3798mv100, bind using
"hisilicon,inno-usb2-phy" compatible and operate correctly, so you
remove hisilicon,hi3798mv100-usb2-phy from the driver and device
operates correctly?

Best regards,
Krzysztof

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