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Date:   Thu, 23 Jun 2022 08:50:31 +0200
From:   Sascha Hauer <sha@pengutronix.de>
To:     Saravana Kannan <saravanak@google.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@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>, Peng Fan <peng.fan@nxp.com>,
        Kevin Hilman <khilman@kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
        Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
        Andrew Lunn <andrew@lunn.ch>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        David Ahern <dsahern@kernel.org>, kernel-team@android.com,
        linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
        iommu@lists.linux-foundation.org, netdev@vger.kernel.org,
        linux-gpio@vger.kernel.org, kernel@pengutronix.de,
        devicetree@vger.kernel.org, linux-acpi@vger.kernel.org
Subject: Re: [PATCH v1 1/2] driver core: fw_devlink: Allow firmware to mark
 devices as best effort
Message-ID: <20220623065031.GX1615@pengutronix.de>
References: <20220622215912.550419-1-saravanak@google.com>
 <20220622215912.550419-2-saravanak@google.com>
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On Wed, Jun 22, 2022 at 02:59:10PM -0700, Saravana Kannan wrote:
> When firmware sets the FWNODE_FLAG_BEST_EFFORT flag for a fwnode,
> fw_devlink will do a best effort ordering for that device where it'll
> only enforce the probe/suspend/resume ordering of that device with
> suppliers that have drivers. The driver of that device can then decide
> if it wants to defer probe or probe without the suppliers.
> 
> This will be useful for avoid probe delays of the console device that
> were caused by commit 71066545b48e ("driver core: Set
> fw_devlink.strict=1 by default").
> 
> Fixes: 71066545b48e ("driver core: Set fw_devlink.strict=1 by default")
> Reported-by: Sascha Hauer <sha@pengutronix.de>
> Reported-by: Peng Fan <peng.fan@nxp.com>
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> ---
>  drivers/base/core.c    | 3 ++-
>  include/linux/fwnode.h | 4 ++++
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 839f64485a55..61edd18b7bf3 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -968,7 +968,8 @@ static void device_links_missing_supplier(struct device *dev)
>  
>  static bool dev_is_best_effort(struct device *dev)
>  {
> -	return fw_devlink_best_effort && dev->can_match;
> +	return (fw_devlink_best_effort && dev->can_match) ||
> +		dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT;

Check for dev->fwnode first. I am running in a NULL pointer exception
here for a device that doesn't have a fwnode.

Sascha


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