From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Lukasz Stelmach <l.stelmach@samsung.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Heikki Krogerus <heikki.krogerus@linux.intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Linus Walleij <linus.walleij@linaro.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
platform-driver-x86@vger.kernel.org,
Marek Szyprowski <m.szyprowski@samsung.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: Re: [PATCH v8 3/6] software node: implement reference properties
Date: Mon, 9 Nov 2020 23:20:13 +0200 [thread overview]
Message-ID: <20201109212013.GN4077@smile.fi.intel.com> (raw)
In-Reply-To: <dleftjv9eenwhp.fsf%l.stelmach@samsung.com>
On Mon, Nov 09, 2020 at 08:47:14PM +0100, Lukasz Stelmach wrote:
> It was <2020-11-09 pon 21:02>, when Andy Shevchenko wrote:
> > On Mon, Nov 09, 2020 at 07:18:37PM +0100, Lukasz Stelmach wrote:
> >> It was <2020-11-09 pon 19:24>, when Andy Shevchenko wrote:
> >> > On Mon, Nov 09, 2020 at 06:02:29PM +0100, Lukasz Stelmach wrote:
> >> >> It was <2019-11-07 czw 20:22>, when Dmitry Torokhov wrote:
...
> > Create GPIO lookup table.
> >
> >> I could use platform_data to pass structures from configfs but
> >> software nodes would let me save some code in the device driver and use
> >> the same paths for both static (DT) and dynamic (configfs)
> >> configuration.
> >>
> >> Probably I have missed something and I will be greatful, if you tell me
> >> where I can find more information about software nodes. There are few
> >> users in the kernel and it isn't obvious for me how to use software
> >> nodes properly.
> >
> > gpiod_add_lookup_table().
> >
>
> Yes, that is exactly what my POC code does now. But having a lookup
> table together with the rest of the device structures has several
> advantages.
>
> 1) The device may be hotpluggable and there is no
> gpiod_remove_lookup_table().
% git grep -n -w gpiod_remove_lookup_table
Or I did get it wrong? Did you mean that the removal is not being called?
> 2) Having the lookup table allocated and managed together with the rest
> of the device seems like a better way to go than on gpio_lookup_list.
Nice, what are you going to do with the rest of lookup tables
(PWM, regulators, etc)? If you convert, convert them all at least.
> 3) As of now I've got a minor issue with device naming. I need to set
> dev_id of the table before the device is ready and only after it is
> ready, its name is set (in the hotpluggable use case).
Hotpluggable devices are very much supported by ACPI assistance. DT I have
heard has overlays. What's the issue?
> 4) Because no other devices would use this lookup table "publishing" it
> rather than keeping together with the device seems at least slightly
> odd.
>
> When the lookup table is attached to the devices and can be passed
> around the final lookup can be done with a function like
>
> static struct gpio_desc *gpiod_find_from_table(struct device *dev,
> const char *con_id, unsigned int idx,
> unsigned long *flags, struct gpiod_lookup *table)
Something sounds fishy about your case. Why do you need to have board code /
platform data in the first place? Sorry, but I didn't get why you should
reconstruct DT (or ACPI) at run-time without using proper framework / feature
(overlays)?
> >>>> At the moment the driver gets the list from fwnode/of_node. The list
> >>>> contain references to phandles which get resolved and and the driver
> >>>> ends up with a bunch of gpio descriptors. Great.
> >>>>
> >>>> This example looks nice but does the code that reads the reference from
> >>>> the gpios property and returns a gpiod actually exist? If it doesn't, I
> >>>> am willing to write it.
> >>>>
> >>>> At first glance it makes more sense to me to pass (struct gpiod_lookup
> >>>> *) instead of (struct software_node *) and make gpiolib's gpiod_find()
> >>>> accept lookup tables as parameter instead of searching the
> >>>> gpio_lookup_list? Or do you think such temporary table should be
> >>>> assembled from the above structure and then used in gpiod_find()?
> >>>>
> >>>> Any other suggestions on how to get a bunch of gpios (the description
> >>>> for gpios is available in the devicetree) for a device described with a
> >>>> software nodes?
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2020-11-09 21:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-08 4:22 [PATCH v8 0/6] software node: add support for reference properties Dmitry Torokhov
2019-11-08 4:22 ` [PATCH v8 1/6] software node: rename is_array to is_inline Dmitry Torokhov
2019-11-08 9:49 ` Rafael J. Wysocki
2019-11-13 6:52 ` Bjørn Mork
2019-11-13 8:08 ` Dmitry Torokhov
[not found] ` <CGME20191212111237eucas1p1a278d2d5d2437e3219896367e82604cc@eucas1p1.samsung.com>
2019-12-12 11:12 ` Marek Szyprowski
2019-12-12 11:28 ` Andy Shevchenko
2019-12-12 16:41 ` Rafael J. Wysocki
2019-12-13 6:47 ` Marek Szyprowski
2019-12-13 8:37 ` Rafael J. Wysocki
2019-12-13 1:24 ` Dmitry Torokhov
2019-12-13 6:44 ` Marek Szyprowski
2019-11-08 4:22 ` [PATCH v8 2/6] software node: allow embedding of small arrays into property_entry Dmitry Torokhov
2019-11-08 4:22 ` [PATCH v8 3/6] software node: implement reference properties Dmitry Torokhov
[not found] ` <CGME20201109170241eucas1p14c2156334d8c6ef15d52664fa4776f41@eucas1p1.samsung.com>
2020-11-09 17:02 ` Lukasz Stelmach
2020-11-09 17:24 ` Andy Shevchenko
[not found] ` <CGME20201109181851eucas1p241de8938e399c0b603c764593b057c41@eucas1p2.samsung.com>
2020-11-09 18:18 ` Lukasz Stelmach
2020-11-09 18:53 ` Dmitry Torokhov
2020-11-09 19:05 ` Andy Shevchenko
2020-11-10 12:39 ` Heikki Krogerus
2020-11-10 12:46 ` Rafael J. Wysocki
[not found] ` <CGME20201109195504eucas1p19d493c947d8752e39c26202cf0978fc0@eucas1p1.samsung.com>
2020-11-09 19:54 ` Lukasz Stelmach
2020-11-09 19:02 ` Andy Shevchenko
[not found] ` <CGME20201109194725eucas1p2cc9357486879a14b2ad2f6ef968ff4b2@eucas1p2.samsung.com>
2020-11-09 19:47 ` Lukasz Stelmach
2020-11-09 21:20 ` Andy Shevchenko [this message]
2019-11-08 4:22 ` [PATCH v8 4/6] platform/x86: intel_cht_int33fe: use inline " Dmitry Torokhov
2019-11-08 4:22 ` [PATCH v8 5/6] software node: remove separate handling of references Dmitry Torokhov
2019-11-08 4:22 ` [PATCH v8 6/6] software node: add basic tests for property entries Dmitry Torokhov
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