Re: [PATCH v3 12/12] mtd: mtdpart: Don't create platform device that'll never probe

From: Maxim Kiselev <bigunclemax@gmail.com>
To: Saravana Kannan <saravanak@google.com>
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	"Sudeep Holla" <sudeep.holla@arm.com>,
	"Cristian Marussi" <cristian.marussi@arm.com>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Bartosz Golaszewski" <brgl@bgdev.pl>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Marc Zyngier" <maz@kernel.org>,
	"Shawn Guo" <shawnguo@kernel.org>,
	"Sascha Hauer" <s.hauer@pengutronix.de>,
	"Pengutronix Kernel Team" <kernel@pengutronix.de>,
	"Fabio Estevam" <festevam@gmail.com>,
	"NXP Linux Team" <linux-imx@nxp.com>,
	"Miquel Raynal" <miquel.raynal@bootlin.com>,
	"Richard Weinberger" <richard@nod.at>,
	"Vignesh Raghavendra" <vigneshr@ti.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Frank Rowand" <frowand.list@gmail.com>,
	"Geert Uytterhoeven" <geert+renesas@glider.be>,
	"Magnus Damm" <magnus.damm@gmail.com>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Daniel Scally" <djrscally@gmail.com>,
	"Heikki Krogerus" <heikki.krogerus@linux.intel.com>,
	"Sakari Ailus" <sakari.ailus@linux.intel.com>,
	"Len Brown" <lenb@kernel.org>, "Rafał Miłecki" <rafal@milecki.pl>,
	"Abel Vesa" <abel.vesa@linaro.org>,
	"Alexander Stein" <alexander.stein@ew.tq-group.com>,
	"Tony Lindgren" <tony@atomide.com>,
	"Geert Uytterhoeven" <geert@linux-m68k.org>,
	"John Stultz" <jstultz@google.com>,
	"Doug Anderson" <dianders@chromium.org>,
	"Guenter Roeck" <linux@roeck-us.net>,
	"Dmitry Baryshkov" <dmitry.baryshkov@linaro.org>,
	"Maxim Kochetkov" <fido_max@inbox.ru>,
	"Luca Weiss" <luca.weiss@fairphone.com>,
	"Colin Foster" <colin.foster@in-advantage.com>,
	"Martin Kepplinger" <martin.kepplinger@puri.sm>,
	"Jean-Philippe Brucker" <jpb@kernel.org>,
	"Vladimir Oltean" <vladimir.oltean@nxp.com>,
	kernel-team@android.com, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org,
	linux-mtd@lists.infradead.org, devicetree@vger.kernel.org,
	linux-renesas-soc@vger.kernel.org, linux-acpi@vger.kernel.org
Subject: Re: [PATCH v3 12/12] mtd: mtdpart: Don't create platform device that'll never probe
Date: Tue, 7 Feb 2023 10:51:41 +0300	[thread overview]
Message-ID: <CALHCpMgC55uTnZKPGdKmSX1f0++bSLp2odBp5gQ1kmg90JuQwQ@mail.gmail.com> (raw)
In-Reply-To: <20230207014207.1678715-13-saravanak@google.com>

вт, 7 февр. 2023 г. в 04:42, Saravana Kannan <saravanak@google.com>:
>
> These "nvmem-cells" platform devices never get probed because there's no
> platform driver for it and it's never used anywhere else. So it's a
> waste of memory. These devices also cause fw_devlink to block nvmem
> consumers of "nvmem-cells" partition from probing because the supplier
> device never probes.
>
> So stop creating platform devices for nvmem-cells partitions to avoid
> wasting memory and to avoid blocking probing of consumers.
>
> Reported-by: Maxim Kiselev <bigunclemax@gmail.com>
> Fixes: bcdf0315a61a ("mtd: call of_platform_populate() for MTD partitions")
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> ---
>  drivers/mtd/mtdpart.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
> index d442fa94c872..85f5ee6f06fc 100644
> --- a/drivers/mtd/mtdpart.c
> +++ b/drivers/mtd/mtdpart.c
> @@ -577,6 +577,7 @@ static int mtd_part_of_parse(struct mtd_info *master,
>  {
>         struct mtd_part_parser *parser;
>         struct device_node *np;
> +       struct device_node *child;
>         struct property *prop;
>         struct device *dev;
>         const char *compat;
> @@ -594,6 +595,15 @@ static int mtd_part_of_parse(struct mtd_info *master,
>         else
>                 np = of_get_child_by_name(np, "partitions");
>
> +       /*
> +        * Don't create devices that are added to a bus but will never get
> +        * probed. That'll cause fw_devlink to block probing of consumers of
> +        * this partition until the partition device is probed.
> +        */
> +       for_each_child_of_node(np, child)
> +               if (of_device_is_compatible(child, "nvmem-cells"))
> +                       of_node_set_flag(child, OF_POPULATED);
> +
>         of_property_for_each_string(np, "compatible", prop, compat) {
>                 parser = mtd_part_get_compatible_parser(compat);
>                 if (!parser)
> --
> 2.39.1.519.gcb327c4b5f-goog
>

Hi, Saravana!

Now it works pretty well. Thank you so much for your efforts.

> Reported-by: Maxim Kiselev <bigunclemax@gmail.com>
> Fixes: bcdf0315a61a ("mtd: call of_platform_populate() for MTD partitions")
> Signed-off-by: Saravana Kannan <saravanak@google.com>

Tested-by: Maksim Kiselev <bigunclemax@gmail.com>