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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Saravana Kannan <saravanak@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	John Stultz <john.stultz@linaro.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Rob Herring <robh+dt@kernel.org>, Andrew Lunn <andrew@lunn.ch>,
	Vladimir Oltean <olteanv@gmail.com>,
	Android Kernel Team <kernel-team@android.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 2/5] driver core: Set deferred probe reason when deferred by driver core
Date: Tue, 14 Sep 2021 09:01:32 +0200	[thread overview]
Message-ID: <CAMuHMdU8n9LH7+sZ-OFuce_y89GsQvt+HGUYdQMYCqOxoM3Y7Q@mail.gmail.com> (raw)
In-Reply-To: <20210914043928.4066136-3-saravanak@google.com>

Hi Saravana,

On Tue, Sep 14, 2021 at 6:39 AM Saravana Kannan <saravanak@google.com> wrote:
> When the driver core defers the probe of a device, set the deferred
> probe reason so that it's easier to debug. The deferred probe reason is
> available in debugfs under devices_deferred.
>
> Signed-off-by: Saravana Kannan <saravanak@google.com>

Thanks for your patch!

> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -955,6 +955,29 @@ static void device_links_missing_supplier(struct device *dev)
>         }
>  }
>
> +/**
> + * dev_set_def_probe_reason - Set the deferred probe reason for a device
> + * @dev: the pointer to the struct device
> + * @fmt: printf-style format string
> + * @...: arguments as specified in the format string
> + *
> + * This is a more caller-friendly version of device_set_deferred_probe_reason()
> + * that takes variable argument inputs similar to dev_info().
> + */
> +static void dev_set_def_probe_reason(const struct device *dev, const char *fmt, ...)

So this is indeed similar to device_set_deferred_probe_reason(),
but the function's name is completely different, unlike e.g.
(v)printf()?

> +{
> +       struct va_format vaf;
> +       va_list args;
> +
> +       va_start(args, fmt);
> +       vaf.fmt = fmt;
> +       vaf.va = &args;
> +
> +       device_set_deferred_probe_reason(dev, &vaf);
> +
> +       va_end(args);
> +}

I think you can just make this a macro wrapper calling
dev_err_probe(dev, -EPROBE_DEFER, fmt, ...).
Or open-code that below.

> +
>  /**
>   * device_links_check_suppliers - Check presence of supplier drivers.
>   * @dev: Consumer device.
> @@ -975,6 +998,7 @@ int device_links_check_suppliers(struct device *dev)
>  {
>         struct device_link *link;
>         int ret = 0;
> +       struct fwnode_handle *sup_fw;
>
>         /*
>          * Device waiting for supplier to become available is not allowed to
> @@ -983,10 +1007,13 @@ int device_links_check_suppliers(struct device *dev)
>         mutex_lock(&fwnode_link_lock);
>         if (dev->fwnode && !list_empty(&dev->fwnode->suppliers) &&
>             !fw_devlink_is_permissive()) {
> +               sup_fw = list_first_entry(&dev->fwnode->suppliers,
> +                                         struct fwnode_link,
> +                                         c_hook)->supplier;
>                 dev_dbg(dev, "probe deferral - wait for supplier %pfwP\n",
> -                       list_first_entry(&dev->fwnode->suppliers,
> -                       struct fwnode_link,
> -                       c_hook)->supplier);
> +                       sup_fw);
> +               dev_set_def_probe_reason(dev,
> +                       "wait for supplier %pfwP\n", sup_fw);

dev_err_probe() would replace both the dev_dbg() and the
dev_set_def_probe_reason().

>                 mutex_unlock(&fwnode_link_lock);
>                 return -EPROBE_DEFER;
>         }
> @@ -1003,6 +1030,9 @@ int device_links_check_suppliers(struct device *dev)
>                         device_links_missing_supplier(dev);
>                         dev_dbg(dev, "probe deferral - supplier %s not ready\n",
>                                 dev_name(link->supplier));
> +                       dev_set_def_probe_reason(dev,
> +                               "supplier %s not ready\n",
> +                               dev_name(link->supplier));

Likewise.

>                         ret = -EPROBE_DEFER;
>                         break;
>                 }

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

  reply	other threads:[~2021-09-14  7:01 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-14  4:39 [PATCH v1 0/5] fw_devlink improvements Saravana Kannan
2021-09-14  4:39 ` [PATCH v1 1/5] driver core: fw_devlink: Improve handling of cyclic dependencies Saravana Kannan
2021-09-14  6:16   ` Marek Szyprowski
2021-09-14  8:01     ` Saravana Kannan
2021-09-14 12:35   ` Rob Herring
2021-09-14 16:23     ` Saravana Kannan
2021-09-14  4:39 ` [PATCH v1 2/5] driver core: Set deferred probe reason when deferred by driver core Saravana Kannan
2021-09-14  7:01   ` Geert Uytterhoeven [this message]
2021-09-14  7:58     ` Saravana Kannan
2021-09-15  5:41       ` Saravana Kannan
2021-09-14  4:39 ` [PATCH v1 3/5] driver core: Create __fwnode_link_del() helper function Saravana Kannan
2021-09-14  7:04   ` Geert Uytterhoeven
2021-09-14  7:46     ` Saravana Kannan
2021-09-14  4:39 ` [PATCH v1 4/5] driver core: Add debug logs when fwnode links are added/deleted Saravana Kannan
2021-09-14  7:09   ` Geert Uytterhoeven
2021-09-14  4:39 ` [PATCH v1 5/5] driver core: Add fw_devlink.debug command line boolean parameter Saravana Kannan
2021-09-14 15:10   ` Andrew Lunn
2021-09-14 16:27     ` Saravana Kannan
2021-09-14 16:43       ` Andrew Lunn
2021-09-14 16:52         ` Rob Herring
2021-09-14 17:31           ` Saravana Kannan

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