linux-kernel - Re: [PATCH 5/7] spi: zynqmp-gqspi: Split the bus

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Message-ID: <0ee72316-11e1-4930-8c49-92db8d148b8a@linux.dev>
Date: Tue, 21 Jan 2025 11:17:03 -0500
From: Sean Anderson <sean.anderson@...ux.dev>
To: Mark Brown <broonie@...nel.org>
Cc: "Mahapatra, Amit Kumar" <amit.kumar-mahapatra@....com>,
 "Simek, Michal" <michal.simek@....com>,
 "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
 Jinjie Ruan <ruanjinjie@...wei.com>,
 "linux-arm-kernel@...ts.infradead.org"
 <linux-arm-kernel@...ts.infradead.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 Miquel Raynal <miquel.raynal@...tlin.com>,
 "amitrkcian2002@...il.com" <amitrkcian2002@...il.com>,
 "git (AMD-Xilinx)" <git@....com>
Subject: Re: [PATCH 5/7] spi: zynqmp-gqspi: Split the bus

On 1/21/25 11:01, Mark Brown wrote:
> On Tue, Jan 21, 2025 at 10:53:53AM -0500, Sean Anderson wrote:
>> On 1/21/25 08:19, Mahapatra, Amit Kumar wrote:
> 
>> > IMHO, restricting users to fixed names is not ideal. A better approach would be to 
>> > introduce a Device Tree (DT) property for the bus number and select the bus 
>> > accordingly.
> 
>> Why? It's not an artificial restriction; it reflects the hardware. And this is how
>> SPI busses are typically represented. If you have two SPI busses, there should be
>> two devicetree nodes.
> 
> Perhaps the thing is more that the buses are named instead of numbered?

Well, we could number them, but it's not like they have different
addresses in memory. They use all the same registers except for a bit in
the genfifo. So it doesn't make sense to do address translation (e.g.
with reg/ranges).

As for the names, these are the names used by the documentation, as well
as the exising driver. There are some references to SPI0/SPI1, but there
are more to upper/lower. If you want to bikeshed spi-0/spi-1 instead of
spi-lower/spi-upper, be my guest.

--Sean