Linux-ACPI Archive on lore.kernel.org
 help / color / Atom feed
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
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



  reply index

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 " 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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201109212013.GN4077@smile.fi.intel.com \
    --to=andriy.shevchenko@linux.intel.com \
    --cc=ard.biesheuvel@linaro.org \
    --cc=b.zolnierkie@samsung.com \
    --cc=dmitry.torokhov@gmail.com \
    --cc=heikki.krogerus@linux.intel.com \
    --cc=l.stelmach@samsung.com \
    --cc=linus.walleij@linaro.org \
    --cc=linux-acpi@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=m.szyprowski@samsung.com \
    --cc=mika.westerberg@linux.intel.com \
    --cc=platform-driver-x86@vger.kernel.org \
    --cc=rafael@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-ACPI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-acpi/0 linux-acpi/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-acpi linux-acpi/ https://lore.kernel.org/linux-acpi \
		linux-acpi@vger.kernel.org
	public-inbox-index linux-acpi

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-acpi


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git