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From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: Stephen Boyd <sboyd@kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Saravana Kannan <saravanak@google.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Tudor Ambarus <tudor.ambarus@microchip.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Frank Rowand <frowand.list@gmail.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	Kevin Hilman <khilman@kernel.org>,
	Len Brown <len.brown@intel.com>, Len Brown <lenb@kernel.org>,
	Marc Zyngier <maz@kernel.org>,
	Michael Turquette <mturquette@baylibre.com>,
	Pavel Machek <pavel@ucw.cz>,
	"Rafael J.Wysocki" <rafael@kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Nicolas Ferre <nicolas.ferre@microchip.com>,
	Claudiu Beznea <claudiu.beznea@microchip.com>,
	DOCUMENTATION <linux-doc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux PM list <linux-pm@vger.kernel.org>,
	linux-clk <linux-clk@vger.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS "
	"<devicetree@vger.ke rnel.org>,
	ACPI Devel Maling List " "<linux-acpi@vger.kernel.org>,
	Android Kernel Team " "<kernel-team@android.com>,
	linux-rpi-kernel"  <linux-rpi-kernel@lists.infradead.org>
Subject: Re: [PATCH] clk: Mark fwnodes when their clock provider is added
Date: Mon, 05 Apr 2021 13:04:40 +0200
Message-ID: <8f147485af325181c57bdf0dd3b0e3dd54000ac8.camel@suse.de> (raw)
In-Reply-To: <161721871083.2260335.2392646934517115770@swboyd.mtv.corp.google.com>


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On Wed, 2021-03-31 at 12:25 -0700, Stephen Boyd wrote:
> Quoting Geert Uytterhoeven (2021-03-31 00:05:00)
> > On Wed, Mar 31, 2021 at 4:22 AM Stephen Boyd <sboyd@kernel.org> wrote:
> > > > > Does it have any use?
> > > > 
> > > > of_clk_del_provider() removes the first provider found with node == NULL.
> > > > If there are two drivers calling of_clk_add_hw_provider(), and one of
> > > > hem calls of_clk_del_provider() later, the wrong provider may be
> > > > removed from the list.
> > > > 
> > > 
> > > So you're saying we shouldn't add a NULL device node pointer to the list
> > > so that this can't happen? That doesn't mean returning an error from
> > > of_clk_add_hw_provider() would be useful though.
> > > of_clk_add_hw_provider() can return 0 if np == NULL and
> > > of_clk_del_provider() can return early if np == NULL too.
> > 
> > I don't know if I grasp all meanings of the above.
> > 
> > The main question is if it is valid for a driver to call
> > of_clk_add_hw_provider()
> > with np == NULL.
> >   - If yes, should that register the provider?
> 
> No it should not register the provider. That would be bad as you pointed
> out.
> 
> >       - If yes, how to handle two drivers calling of_clk_add_hw_provider()
> >         with np = NULL, as their unregistration order is not guaranteed to
> >         be correct.
> > 
> > If no, is that something to ignore (0), or a bug (error)?
> 
> This is my question above. Is there a use to having
> of_clk_add_hw_provider() return an error value when np == NULL? I doubt
> it.
> 
> Returning 0 would reduce the if conditions in driver code in this case
> and be consistent with the CONFIG_OF=n inline stub that returns 0 when
> CONFIG_OF is disabled. The only case an error would be returned is if we
> couldn't allocate memory or if the assigned clocks code failed. Seems
> sane to me. The downside is that drivers would maybe register clkdev
> lookups when they don't need to and waste some memory. I'm fine with
> that until we have some sort of non-DT based clk provider lookup
> mechanism that could unify the two methods.

What about devm_of_clk_add_hw_provider() users, do we care that a seemingly
empty managed resource will be created?

Regards,
Nicolas


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  parent reply index

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20210205222651eucas1p28ef87073dea33c1c5224c14aa203bec5@eucas1p2.samsung.com>
2021-02-05 22:26 ` [PATCH v4 0/8] Make fw_devlink=on more forgiving Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 1/8] driver core: fw_devlink: Detect supplier devices that will never be added Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 2/8] of: property: Don't add links to absent suppliers Saravana Kannan
2021-02-09 21:25     ` Rob Herring
2021-02-05 22:26   ` [PATCH v4 3/8] driver core: Add fw_devlink.strict kernel param Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 4/8] of: property: Add fw_devlink support for optional properties Saravana Kannan
2021-02-09 21:33     ` Rob Herring
2021-02-09 21:54       ` Saravana Kannan
2021-02-10  8:25         ` Geert Uytterhoeven
2021-02-05 22:26   ` [PATCH v4 5/8] driver core: fw_devlink: Handle suppliers that don't use driver core Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 6/8] irqdomain: Mark fwnodes when their irqdomain is added/removed Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 7/8] PM: domains: Mark fwnodes when their powerdomain " Saravana Kannan
2021-02-05 22:26   ` [PATCH v4 8/8] clk: Mark fwnodes when their clock provider " Saravana Kannan
2021-02-08 15:38     ` Rob Herring
2021-02-08 23:34       ` Saravana Kannan
2021-02-10 11:44     ` [PATCH] clk: Mark fwnodes when their clock provider is added Tudor Ambarus
2021-02-10 11:44       ` Tudor Ambarus
2021-02-11 13:00         ` Greg KH
2021-02-13  0:37           ` Stephen Boyd
     [not found]         ` <CGME20210325133159eucas1p297b769beb681743fb32d362a86cc6e3e@eucas1p2.samsung.com>
2021-03-25 13:31           ` Marek Szyprowski
2021-03-25 15:47             ` Geert Uytterhoeven
2021-03-25 18:25             ` Nicolas Saenz Julienne
2021-03-26 18:13               ` Stephen Boyd
2021-03-26 18:29                 ` Geert Uytterhoeven
     [not found]                   ` <161705310317.3012082.15148238105608149214@swboyd.mtv.corp.google.com>
2021-03-29 23:28                     ` Saravana Kannan
     [not found]                       ` <161706920822.3012082.10047587064612237296@swboyd.mtv.corp.google.com>
2021-03-30  6:58                         ` Geert Uytterhoeven
     [not found]                           ` <161715734080.2260335.881350237641202575@swboyd.mtv.corp.google.com>
2021-03-31  7:05                             ` Geert Uytterhoeven
     [not found]                               ` <161721871083.2260335.2392646934517115770@swboyd.mtv.corp.google.com>
2021-04-05 11:04                                 ` Nicolas Saenz Julienne [this message]
2021-04-21  3:26         ` Guenter Roeck
2021-04-21  7:00           ` Saravana Kannan
2021-02-10 19:13       ` Saravana Kannan
2021-03-30 15:42       ` Guenter Roeck
2021-03-30 16:26         ` Saravana Kannan
     [not found]     ` <161317679292.1254594.15797939257637374295@swboyd.mtv.corp.google.com>
2021-02-14 21:15       ` [PATCH v4 8/8] clk: Mark fwnodes when their clock provider is added/removed Saravana Kannan
2021-02-06  2:45   ` [PATCH v4 0/8] Make fw_devlink=on more forgiving Saravana Kannan
2021-02-06 19:41   ` Geert Uytterhoeven
2021-02-06 20:47     ` Saravana Kannan
2021-02-08  8:40   ` Marek Szyprowski
2021-02-08 23:57     ` Saravana Kannan
2021-02-10  8:19   ` Tudor.Ambarus
2021-02-10  8:54     ` Saravana Kannan
2021-02-10 10:02       ` Tudor.Ambarus
2021-02-10 19:14         ` Saravana Kannan
2021-02-11 13:00   ` Geert Uytterhoeven
2021-02-11 13:05     ` Geert Uytterhoeven
2021-02-12  2:59     ` Saravana Kannan
2021-02-12  8:14       ` Geert Uytterhoeven
2021-02-12 20:57         ` Saravana Kannan
2021-02-15 12:38       ` Geert Uytterhoeven
2021-02-15 21:26         ` Saravana Kannan
2021-02-16  8:05           ` Geert Uytterhoeven
2021-02-16 18:48             ` Saravana Kannan
2021-02-16 20:31               ` Geert Uytterhoeven
2021-02-17 23:57                 ` Saravana Kannan
2021-02-25  9:21                   ` Geert Uytterhoeven
2021-02-15 15:16       ` Geert Uytterhoeven
2021-02-15 21:57         ` Saravana Kannan
2021-02-16 12:58           ` Geert Uytterhoeven
2021-02-15 11:19     ` Geert Uytterhoeven

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