Linux-i3c Archive on lore.kernel.org
 help / color / Atom feed
From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	"Kieran Bingham" <kieran@ksquared.org.uk>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Jacopo Mondi" <jacopo@jmondi.org>,
	"Vladimir Zapolskiy" <vz@mleia.com>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	"Luca Ceresoli" <luca@lucaceresoli.net>,
	"Linux I2C" <linux-i2c@vger.kernel.org>,
	"Niklas Söderlund" <niklas.soderlund@ragnatech.se>,
	linux-i3c@lists.infradead.org,
	"Laurent Pinchart" <laurent.pinchart@ideasonboard.com>
Subject: Re: [RFC PATCH 3/7] i2c: allow DT nodes without 'compatible'
Date: Fri, 21 Feb 2020 10:45:57 +0100
Message-ID: <CAMuHMdWaPfc050dZiRr+gAFzsdjSo9Vo70ztWgrMGPJxLUqupw@mail.gmail.com> (raw)
In-Reply-To: <20200220172403.26062-4-wsa+renesas@sang-engineering.com>

Hi Wolfram,

On Thu, Feb 20, 2020 at 6:26 PM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
> Sometimes, we have unknown devices in a system and still want to block
> their address. For that, we allow DT nodes with only a 'reg' property.
> These devices will be bound to the "dummy" driver but with the name
> "reserved". That way, we can distinguish them and even hand them over to
> the "dummy" driver later when they are really requested using
> i2c_new_ancillary_device().
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Thanks for your patch!

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
but one question below.

> --- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> @@ -50,7 +50,6 @@ Examples:
>                 reg-io-width = <1>;     /* 8 bit read/write */
>
>                 dummy@60 {
> -                       compatible = "dummy";
>                         reg = <0x60>;
>                 };
>         };

There's a second instance to remove 18 lines below.

> --- a/drivers/i2c/i2c-core-of.c
> +++ b/drivers/i2c/i2c-core-of.c
> @@ -27,17 +27,15 @@ int of_i2c_get_board_info(struct device *dev, struct device_node *node,
>
>         memset(info, 0, sizeof(*info));
>
> -       if (of_modalias_node(node, info->type, sizeof(info->type)) < 0) {
> -               dev_err(dev, "of_i2c: modalias failure on %pOF\n", node);
> -               return -EINVAL;
> -       }
> -
>         ret = of_property_read_u32(node, "reg", &addr);
>         if (ret) {
>                 dev_err(dev, "of_i2c: invalid reg on %pOF\n", node);
>                 return ret;
>         }
>
> +       if (of_modalias_node(node, info->type, sizeof(info->type)) < 0)
> +               strlcpy(info->type, I2C_RESERVED_DRV_NAME, sizeof(I2C_RESERVED_DRV_NAME));

Could this cause a regression, e.g. if people already have such dummy
nodes in their DTS, and use sysfs new_device from userspace to
instantiate the device later?

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

_______________________________________________
linux-i3c mailing list
linux-i3c@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-i3c

  reply index

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-20 17:23 [RFC PATCH 0/7] i2c: of: reserve unknown and ancillary addresses Wolfram Sang
2020-02-20 17:23 ` [RFC PATCH 1/7] i2c: add sanity check for parameter of i2c_verify_client() Wolfram Sang
2020-02-21  9:36   ` Geert Uytterhoeven
2020-02-20 17:23 ` [RFC PATCH 2/7] i2c: use DEFINE for the dummy driver name Wolfram Sang
2020-02-21  9:38   ` Geert Uytterhoeven
2020-02-20 17:23 ` [RFC PATCH 3/7] i2c: allow DT nodes without 'compatible' Wolfram Sang
2020-02-21  9:45   ` Geert Uytterhoeven [this message]
2020-02-21  9:48     ` Geert Uytterhoeven
2020-02-23 23:11     ` Luca Ceresoli
2020-03-12 11:19       ` Wolfram Sang
2020-03-12 11:44         ` Alexandre Belloni
2020-04-10 13:47         ` Luca Ceresoli
2020-02-26 16:30   ` Rob Herring
2020-02-20 17:24 ` [RFC PATCH 4/7] i2c: of: remove superfluous parameter from exported function Wolfram Sang
2020-02-21  9:50   ` Geert Uytterhoeven
2020-02-24  8:12   ` Luca Ceresoli
2020-02-20 17:24 ` [RFC PATCH 5/7] i2c: of: error message unification Wolfram Sang
2020-02-21  9:54   ` Geert Uytterhoeven
2020-02-20 17:24 ` [RFC PATCH 6/7] i2c: of: mark a whole array of regs as reserved Wolfram Sang
2020-02-21 10:09   ` Geert Uytterhoeven
2020-03-12 11:21     ` Wolfram Sang
2020-03-18 14:33     ` Wolfram Sang
2020-02-28 12:11   ` Luca Ceresoli
2020-02-20 17:24 ` [RFC PATCH 7/7] i2c: core: hand over reserved devices when requesting ancillary addresses Wolfram Sang
2020-02-21 10:13   ` Geert Uytterhoeven
2020-02-28 12:11     ` Luca Ceresoli
2020-03-12 11:30       ` Wolfram Sang
2020-03-12 11:21     ` Wolfram Sang
2020-03-13 12:42     ` Wolfram Sang
2020-02-21 10:15 ` [RFC PATCH 0/7] i2c: of: reserve unknown and " Geert Uytterhoeven

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=CAMuHMdWaPfc050dZiRr+gAFzsdjSo9Vo70ztWgrMGPJxLUqupw@mail.gmail.com \
    --to=geert@linux-m68k.org \
    --cc=devicetree@vger.kernel.org \
    --cc=jacopo@jmondi.org \
    --cc=kieran@ksquared.org.uk \
    --cc=laurent.pinchart@ideasonboard.com \
    --cc=linux-i2c@vger.kernel.org \
    --cc=linux-i3c@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-renesas-soc@vger.kernel.org \
    --cc=luca@lucaceresoli.net \
    --cc=niklas.soderlund@ragnatech.se \
    --cc=vz@mleia.com \
    --cc=wsa+renesas@sang-engineering.com \
    /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-i3c Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-i3c/0 linux-i3c/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-i3c linux-i3c/ https://lore.kernel.org/linux-i3c \
		linux-i3c@lists.infradead.org
	public-inbox-index linux-i3c

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-i3c


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