linux-kernel - Re: [PATCH v2 6/7] platform: x86: Add intel_skl

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Date:   Tue, 19 Jan 2021 13:08:37 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Daniel Scally <djrscally@...il.com>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-i2c@...r.kernel.org,
        platform-driver-x86@...r.kernel.org, devel@...ica.org,
        rjw@...ysocki.net, lenb@...nel.org, andy@...nel.org,
        mika.westerberg@...ux.intel.com, linus.walleij@...aro.org,
        bgolaszewski@...libre.com, wsa@...nel.org, lee.jones@...aro.org,
        hdegoede@...hat.com, mgross@...ux.intel.com,
        robert.moore@...el.com, erik.kaneda@...el.com,
        sakari.ailus@...ux.intel.com, kieran.bingham@...asonboard.com
Subject: Re: [PATCH v2 6/7] platform: x86: Add intel_skl_int3472 driver

On Tue, Jan 19, 2021 at 10:40:42AM +0000, Daniel Scally wrote:
> On 19/01/2021 09:24, Andy Shevchenko wrote:
> >>>>> +static struct i2c_driver int3472_tps68470 = {
> >>>>> +	.driver = {
> >>>>> +		.name = "int3472-tps68470",
> >>>>> +		.acpi_match_table = int3472_device_id,
> >>>>> +	},
> >>>>> +	.probe_new = skl_int3472_tps68470_probe,
> >>>>> +};
> >>> I'm not sure we want to have like this. If I'm not mistaken the I²C driver can
> >>> be separated without ACPI IDs (just having I²C IDs) and you may instantiate it
> >>> via i2c_new_client_device() or i2c_acpi_new_device() whichever suits better...
> >> Sorry, I'm a bit confused by this. The i2c device is already
> >> present...we just want the driver to bind to them, so what role do those
> >> functions have there?
> > What I meant is something like
> >
> >  *_i2c.c
> > 	real I²C driver for the TPS chip, but solely with I²C ID table, no ACPI
> > 	involved (and it sounds like it should be mfd/tps one, in which you
> > 	just cut out ACPI IDs and convert to pure I²C one, that what I had
> > 	suggested in the first place)
> 
> Ahh; sorry - i misunderstood what you meant there. I understand now I
> think, but there is one complication; the ACPI subsystem already creates
> a client for that i2c adapter and address; i2c_new_client_device()
> includes a check to see whether that adapter / address combination has
> an i2c device already.  So we would have to have the platform driver
> with ACPI ID first find the existing i2c_client and unregister it before
> registering the new one...the existing clients have a name matching the
> ACPI device instance name (e.g i2c-INT3472:00) which we can't use as an
> i2c_device_id of course.

See how INT33FE is being handled. Hint: drivers/acpi/scan.c:~1600

static const struct acpi_device_id i2c_multi_instantiate_ids[] = {
	{"BSG1160", },
	{"BSG2150", },
	{"INT33FE", },
	{"INT3515", },
	{}
};

So, we quirklist it here and instantiate manually from platform driver (new
coming one).

...

> > You need to modify clk-gpio.c to export
> >
> > clk_hw_register_gpio_gate()
> > clk_hw_register_gpio_mux()
> >
> > (perhaps it will require to add *_unregister() counterparts) and call it from
> > your code.
> >
> > See, for example, how clk_hw_unregister_fixed_rate() is being used. Another

Here I meant of course clk_hw_register_fixed_rate().

> > case is to add a helper directly into clk-gpio and call it instead of
> > clk_hw_*() one, see how clk_register_fractional_divider() is implemented and
> > used.
> 
> I'll take a look, thanks

-- 
With Best Regards,
Andy Shevchenko