From: Ulf Hansson <ulf.hansson@linaro.org>
To: Saravana Kannan <saravanak@google.com>
Cc: Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Android Kernel Team <kernel-team@android.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
DTML <devicetree@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] of: platform: Make sure bus only devices get probed
Date: Fri, 3 Sep 2021 11:18:48 +0200 [thread overview]
Message-ID: <CAPDyKFpP6pSRSw8_OAW8+ZJNH+CwXtfWBNDcD182gQmzqW=O5g@mail.gmail.com> (raw)
In-Reply-To: <20210902230442.1515531-2-saravanak@google.com>
On Fri, 3 Sept 2021 at 01:04, Saravana Kannan <saravanak@google.com> wrote:
>
> fw_devlink could end up creating device links for bus only devices.
> However, bus only devices don't get probed and can block probe() or
> sync_state() [1] call backs of other devices. To avoid this, set up
> these devices to get probed by the simple-pm-bus.
>
> [1] - https://lore.kernel.org/lkml/CAPDyKFo9Bxremkb1dDrr4OcXSpE0keVze94Cm=zrkOVxHHxBmQ@mail.gmail.com/
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> Tested-by: Saravana Kannan <saravanak@google.com>
Again, this looks like a nice solution to the problem.
One question though. The Kconfig SIMPLE_PM_BUS, should probably be
"default y" - or something along those lines to make sure fw_devlink
works as expected.
Kind regards
Uffe
> ---
> drivers/of/platform.c | 45 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 45 insertions(+)
>
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 74afbb7a4f5e..b010e2310131 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -97,6 +97,48 @@ static void of_device_make_bus_id(struct device *dev)
> }
> }
>
> +/**
> + * of_match_only_simple_bus - Check if a device node is only a simple bus
> + * @np: device node to check
> + *
> + * A simple bus in this context is defined as a transparent bus whose child
> + * devices are automatically populated but has no hardware specific
> + * functionality.
> + *
> + * Returns true if the device node is only a simple bus and can never match
> + * with any other specific driver. Otherwise, returns false.
> + */
> +static bool of_match_only_simple_bus(struct device_node *np)
> +{
> + /* List of buses that don't have an explicit driver. */
> + static const char * const of_simple_bus_table[] = {
> + "simple-bus",
> + "simple-mfd",
> + "isa",
> + "arm,amba-bus",
> + };
> + const char *cp;
> + struct property *prop;
> + int i;
> +
> + prop = of_find_property(np, "compatible", NULL);
> + for (cp = of_prop_next_string(prop, NULL); cp;
> + cp = of_prop_next_string(prop, cp)) {
> + bool match = false;
> + const char *bus = of_simple_bus_table[i];
> +
> + for (i = 0; i < ARRAY_SIZE(of_simple_bus_table); i++)
> + if (!of_compat_cmp(cp, bus, strlen(bus))) {
> + match = true;
> + break;
> + }
> + if (!match)
> + return false;
> + }
> +
> + return true;
> +}
> +
> /**
> * of_device_alloc - Allocate and initialize an of_device
> * @np: device node to assign to device
> @@ -143,6 +185,9 @@ struct platform_device *of_device_alloc(struct device_node *np,
> dev->dev.fwnode = &np->fwnode;
> dev->dev.parent = parent ? : &platform_bus;
>
> + if (of_match_only_simple_bus(np))
> + dev->driver_override = "simple-pm-bus";
> +
> if (bus_id)
> dev_set_name(&dev->dev, "%s", bus_id);
> else
> --
> 2.33.0.153.gba50c8fa24-goog
>
next prev parent reply other threads:[~2021-09-03 9:19 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-02 23:04 [PATCH v2 0/2] Fix simple-bus issues with fw_devlink Saravana Kannan
2021-09-02 23:04 ` [PATCH v2 1/2] of: platform: Make sure bus only devices get probed Saravana Kannan
2021-09-03 9:18 ` Ulf Hansson [this message]
2021-09-03 14:29 ` Geert Uytterhoeven
2021-09-03 17:09 ` Saravana Kannan
2021-09-03 19:06 ` Geert Uytterhoeven
2021-09-03 19:08 ` Saravana Kannan
2021-09-07 10:35 ` Ulf Hansson
2021-09-07 10:52 ` Geert Uytterhoeven
2021-09-07 11:02 ` Ulf Hansson
2021-09-02 23:04 ` [PATCH v2 2/2] drivers: bus: simple-pm-bus: Add support for probing simple bus only devices Saravana Kannan
2021-09-03 9:14 ` Ulf Hansson
2021-09-03 17:10 ` Saravana Kannan
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