linux-kernel - Re: [PATCH v3 6/9] mfd: intel-m10-bmc: Downscope SPI defines & prefix with M10BMC

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Message-ID: <b09aabe4-3f82-70f0-aca2-f1cdf7d6a26@linux.intel.com>
Date:   Mon, 5 Dec 2022 11:31:06 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Russ Weight <russell.h.weight@...el.com>
cc:     Xu Yilun <yilun.xu@...el.com>, linux-fpga@...r.kernel.org,
        Wu Hao <hao.wu@...el.com>, Tom Rix <trix@...hat.com>,
        Moritz Fischer <mdf@...nel.org>, Lee Jones <lee@...nel.org>,
        Matthew Gerlach <matthew.gerlach@...ux.intel.com>,
        Tianfei zhang <tianfei.zhang@...el.com>,
        Mark Brown <broonie@...nel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Marco Pagani <marpagan@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 6/9] mfd: intel-m10-bmc: Downscope SPI defines & prefix
 with M10BMC_SPI

On Fri, 2 Dec 2022, Russ Weight wrote:
> On 12/2/22 08:28, Xu Yilun wrote:
> > On 2022-12-02 at 12:08:38 +0200, Ilpo Järvinen wrote:
> >> Move SPI based board definitions to per interface file from the global
> >> header. This makes it harder to use them accidently in the
> >> generic/interface agnostic code. Prefix the defines with M10BMC_SPI
> > I'm not sure if the register layout is actually bound to the bus
> > interface. My experience is the register layout is always decided by
> > board type. Is it possible there will be a new SPI based board but
> > has different register layout in future?
> >
> > So is M10BMC_SPI_XXX a good nam
> 
> There could be future devices, spi or pmci based, that require different
> addresses for some of these values, and at that time we would need to
> additional versions of some of these macros using different names.
> Right now, spi and pmci are the primary differentiating factors. I'm not
> sure how to improve on the naming. Do you have any suggestions?

It's per board type yes, but there's a strong clustering currently on 
spi/pmci differentiation. That implies a one define applies to multiple 
board types so naming it, e.g., after a single board type seems not much 
better than the current approach.

I've even thought myself of removing those defines as they seem one-time 
use ones after introducing the csr_map. Defining the csr_map using members
kinda documents what a literal is about if I'd put just a number there.
The added benefit a few capital letters in a define provides is IMHO very
questionable.

Also m10bmc_spi_csr_map name suffers from the same problem, BTW.

I could, of course now that they're downscoped, drop _SPI_ or _PMCI_ from 
their names if that's ok for you? ...But that wouldn't address the next 
version naming problem at all. But I don't anyway know, without a crystal 
ball, know how to address the future naming needs.

-- 
 i.