linux-kernel - Re: [PATCH] virtio: don't fail on !of_device_is

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Message-ID: <20210913205322.GA1076369@roeck-us.net>
Date:   Mon, 13 Sep 2021 13:53:22 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Alexey Kardashevskiy <aik@...abs.ru>,
        Jason Wang <jasowang@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Arnd Bergmann <arnd@...nel.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Bill Mills <bill.mills@...aro.org>,
        Alex Bennée <alex.bennee@...aro.org>,
        "Enrico Weigelt, metux IT consult" <info@...ux.net>,
        Jie Deng <jie.deng@...el.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH] virtio: don't fail on !of_device_is_compatible

On Mon, Sep 13, 2021 at 06:47:46AM -0400, Michael S. Tsirkin wrote:
> A recent change checking of_device_is_compatible on probe broke some
> powerpc/pseries setups. Apparently there virtio devices do not have a
> "compatible" property - they are matched by PCI vendor/device ids.
> 
> Let's just skip of_node setup but proceed with initialization like we
> did previously.
> 
> Fixes: 694a1116b405 ("virtio: Bind virtio device to device-tree node")
> Reported-by: Alexey Kardashevskiy <aik@...abs.ru>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Viresh Kumar <viresh.kumar@...aro.org>
> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
> ---

This patch also fixes a similar problem seen with sparc64.

Tested-by: Guenter Roeck <linux@...ck-us.net>

Guenter

> 
> Arnd could you help review this pls? Viresh is on vacation.
> 
>  drivers/virtio/virtio.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> index c46cc1fbc7ae..19a70a2361b4 100644
> --- a/drivers/virtio/virtio.c
> +++ b/drivers/virtio/virtio.c
> @@ -347,8 +347,13 @@ static int virtio_device_of_init(struct virtio_device *dev)
>  	ret = snprintf(compat, sizeof(compat), "virtio,device%x", dev->id.device);
>  	BUG_ON(ret >= sizeof(compat));
>  
> +	/*
> +	 * On powerpc/pseries virtio devices are PCI devices so PCI
> +	 * vendor/device ids play the role of the "compatible" property.
> +	 * Simply don't init of_node in this case.
> +	 */
>  	if (!of_device_is_compatible(np, compat)) {
> -		ret = -EINVAL;
> +		ret = 0;
>  		goto out;
>  	}
>  
> -- 
> MST
>