linux-kernel - Re: [PATCH v3 net-next 08/14] net: dsa: felix: update init

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Message-ID: <YzNEYiXx6UoJLEdk@colin-ia-desktop>
Date:   Tue, 27 Sep 2022 11:43:46 -0700
From:   Colin Foster <colin.foster@...advantage.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, netdev@...r.kernel.org,
        Russell King <linux@...linux.org.uk>,
        Linus Walleij <linus.walleij@...aro.org>,
        UNGLinuxDriver@...rochip.com,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Lee Jones <lee@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH v3 net-next 08/14] net: dsa: felix: update init_regmap to
 be string-based

Hi Vladimir,

On Tue, Sep 27, 2022 at 08:53:53PM +0300, Vladimir Oltean wrote:
> Hi Colin,
> 
> On Sun, Sep 25, 2022 at 05:29:22PM -0700, Colin Foster wrote:
> > During development, it was believed that a wrapper for ocelot_regmap_init()
> > would be sufficient for the felix driver to work in non-mmio scenarios.
> > This was merged in during commit 242bd0c10bbd ("net: dsa: ocelot: felix:
> > add interface for custom regmaps")
> > 
> > As the external ocelot DSA driver grew closer to an acceptable state, it
> > was realized that most of the parameters that were passed in from struct
> > resource *res were useless and ignored. This is due to the fact that the
> > external ocelot DSA driver utilizes dev_get_regmap(dev, resource->name).
> > 
> > Instead of simply ignoring those parameters, refactor the API to only
> > require the name as an argument. MMIO scenarios this will reconstruct the
> > struct resource before calling ocelot_regmap_init(ocelot, resource). MFD
> > scenarios need only call dev_get_regmap(dev, name).
> > 
> > Signed-off-by: Colin Foster <colin.foster@...advantage.com>
> > ---
> 
> I don't like how this turned out. I was expecting you not to look at the
> exported resources from the ocelot-core anymore - that was kind of the
> point of using just the names rather than the whole resource definitions.

I see your point. The init_regmap(name) interface collides with the
*_io_res arrays. Changing the init_regmap() interface doesn't really
change the underlying issue - *_io_res[] is the thing that you're
suggesting to go.

I'm interested to see where this is going. I feel like it might be a
constant names[] array, then felix_vsc9959_init_regmap() where the
specific name <> resource mapping happens. Maybe a common
felix_match_resource_to_name(name, res, len)?

That would definitely remove the need for exporting the
vsc7512_*_io_res[] arrays, which I didn't understand from your v1
review.


Something like:
include/soc/mscc/ocelot.h
#define OCELOT_RES_NAME_ANA "ana"

const char *ocelot_target_names[TARGET_MAX] = {[ANA] = OCELOT_RES_NAME_ANA};

...


drivers/net/dsa/ocelot/felix.c
for (i = 0; i < TARGET_MAX; i++)
    target = felix->info->init_regmap(ocelot_target_names[i]);

...


drivers/net/dsa/ocelot/felix_vsc9959.c
static const struct resource vsc9959_target_io_res[TARGET_MAX] = ...;

vsc9959_init_regmap(name)
{
    /* more logic for port_io_res, but you get the point */
    return felix_init_regmap(name, &vsc9959_target_io_res, TARGET_MAX);
}


> 
> I am also sorry for the mess that the felix driver currently is in, and
> the fact that some things may have confused you.

Vladimir, you might be the last person on earth who owes me an apology.