linux-kernel - RE: [PATCH] dt-bindings: spi: xilinx: Add clocks & clock-names properties

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Message-ID:
 <IA0PR12MB769964FA23FA8B889B47539DDC712@IA0PR12MB7699.namprd12.prod.outlook.com>
Date: Thu, 3 Oct 2024 06:23:07 +0000
From: "Mahapatra, Amit Kumar" <amit.kumar-mahapatra@....com>
To: Conor Dooley <conor@...nel.org>
CC: Krzysztof Kozlowski <krzk@...nel.org>, "broonie@...nel.org"
	<broonie@...nel.org>, "robh@...nel.org" <robh@...nel.org>,
	"krzk+dt@...nel.org" <krzk+dt@...nel.org>, "conor+dt@...nel.org"
	<conor+dt@...nel.org>, "Simek, Michal" <michal.simek@....com>,
	"linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "git (AMD-Xilinx)" <git@....com>,
	"amitrkcian2002@...il.com" <amitrkcian2002@...il.com>
Subject: RE: [PATCH] dt-bindings: spi: xilinx: Add clocks & clock-names
 properties

Hello Conor,

> -----Original Message-----
> From: Conor Dooley <conor@...nel.org>
> Sent: Monday, September 30, 2024 10:10 PM
> To: Mahapatra, Amit Kumar <amit.kumar-mahapatra@....com>
> Cc: Krzysztof Kozlowski <krzk@...nel.org>; broonie@...nel.org; robh@...nel.org;
> krzk+dt@...nel.org; conor+dt@...nel.org; Simek, Michal
> <michal.simek@....com>; linux-spi@...r.kernel.org; devicetree@...r.kernel.org;
> linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; git (AMD-Xilinx)
> <git@....com>; amitrkcian2002@...il.com
> Subject: Re: [PATCH] dt-bindings: spi: xilinx: Add clocks & clock-names properties
> 
> On Mon, Sep 30, 2024 at 03:44:47PM +0000, Mahapatra, Amit Kumar wrote:
> > Hello Conor,
> >
> > > > >>>> Subject: Re: [PATCH] dt-bindings: spi: xilinx: Add clocks &
> > > > >>>> clock-names properties
> > > > >>>>
> > > > >>>> On Mon, Sep 23, 2024 at 06:02:42PM +0530, Amit Kumar Mahapatra
> wrote:
> > > > >>>>> Include the 'clocks' and 'clock-names' properties in the AXI
> > > > >>>>> Quad-SPI bindings. When the AXI4-Lite interface is enabled,
> > > > >>>>> the core operates in legacy mode, maintaining backward
> > > > >>>>> compatibility with version 1.00, and uses 's_axi_aclk' and
> > > > >>>>> 'ext_spi_clk'. For the AXI interface, it uses 's_axi4_aclk' and
> 'ext_spi_clk'.
> > >
> > > > >>>>> +      properties:
> > > > >>>>> +        clock-names:
> > > > >>>>> +          items:
> > > > >>>>> +            - const: s_axi_aclk
> > > > >>>>> +            - const: ext_spi_clk
> > > > >>>>
> > > > >>>> These are all clocks, there should be no need to have "clk" in the names.
> > > > >>>
> > > > >>> These are the names exported by the IP and used by the DTG.
> > > > >>
> > > > >> So? This is a binding, not a verilog file.
> > > > >
> > > > > Axi Quad SPI is an FPGA-based IP, and the clock names are
> > > > > derived from the IP signal names as specified in the IP documentation [1].
> > > > > We chose these names to ensure alignment with the I/O signal
> > > > > names listed in Table 2-2 on page 19 of [1].
> > > > >
> > > > > [1]
> > > > > chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.amd.
> > > > > com/content/dam/xilinx/support/documents/ip_documentation/axi_qu
> > > > > ad_s
> > > > > pi/v3_2/pg153-axi-quad-spi.pdf
> > > >
> > > > So if hardware engineers call them "pink_pony_clk_aclk_really_clk"
> > > > we should follow...
> > > >
> > > >  - bus or axi
> > > >  - ext_spi or spi
> > > >
> > > > You have descriptions of each item to reference real signals.
> > > > Conor's comment is valid - do no make it verilog file.
> > > >
> > > > >
> > > > >>
> > > > >>>>> +
> > > > >>>>> +    else:
> > > > >>>>> +      properties:
> > > > >>>>> +        clock-names:
> > > > >>>>> +          items:
> > > > >>>>> +            - const: s_axi4_aclk
> > > > >>>>> +            - const: ext_spi_clk
> > > >
> > > > Nah, these are the same.
> > >
> > > They may be different, depending on whether or not the driver has to
> > > handle "axi4- lite" versus "axi" differently. That said, I find the
> > > commit message kinda odd in that it states that axi4-lite goes with the s_axi_aclk
> clock and axi goes with s_axi4_aclk.
> >
> > Apologies for the typo. When the AXI4 interface is enabled, it uses
> > s_axi4_aclk, and when the AXI4-Lite interface is enabled, it uses s_axi_aclk.
> >
> > In my next series I will update my commit message & change the
> > clock-names 's_axi4_aclk', 's_axi_aclk' & 'ext_spi_clk' to 'axi4',
> > 'axi' & 'ref' respectively
> 
> There's no driver here, so it is hard to know (why isn't there?) - are you using the axi

We are working on the driver. Once it is ready we will send it to upstream.

> v axi4 to do some sort of differentiation in the driver?
In the driver we don't do any different operations based on the clocks , 
we simply enable the available clocks in the driver.

Regards,
Amit