Subject: Re: [PATCH 1/3] of: base: add support to get machine compatible
 string
To: Sekhar Nori <nsekhar@ti.com>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Kevin Hilman <khilman@baylibre.com>,
        Michael Turquette <mturquette@baylibre.com>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Peter Ujfalusi <peter.ujfalusi@ti.com>,
        Russell King <linux@armlinux.org.uk>
References: <1479811311-3080-1-git-send-email-bgolaszewski@baylibre.com>
 <1479811311-3080-2-git-send-email-bgolaszewski@baylibre.com>
 <5ce9fb9f-459a-562b-2e9f-85d35f9ec035@arm.com>
 <67a3c2c7-0cb9-9764-2710-6ee66fc4dde4@ti.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>,
        LKML <linux-kernel@vger.kernel.org>,
        arm-soc <linux-arm-kernel@lists.infradead.org>,
        linux-drm <dri-devel@lists.freedesktop.org>,
        linux-devicetree <devicetree@vger.kernel.org>,
        Jyri Sarha <jsarha@ti.com>, Tomi Valkeinen <tomi.valkeinen@ti.com>,
        David Airlie <airlied@linux.ie>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Robin Murphy <robin.murphy@arm.com>
From: Sudeep Holla <sudeep.holla@arm.com>
Organization: ARM
Message-ID: <fdb93150-9089-c7bb-2b0a-21ded241a647@arm.com>
Date: Tue, 22 Nov 2016 15:46:25 +0000
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.4.0
MIME-Version: 1.0
In-Reply-To: <67a3c2c7-0cb9-9764-2710-6ee66fc4dde4@ti.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1645
Lines: 56

Hi Sekhar,

On 22/11/16 15:06, Sekhar Nori wrote:
> Hi Sudeep,
>
> On Tuesday 22 November 2016 04:23 PM, Sudeep Holla wrote:
>>
>>
>> On 22/11/16 10:41, Bartosz Golaszewski wrote:
>>> Add a function allowing to retrieve the compatible string of the root
>>> node of the device tree.
>>>
>>
>> Rob has queued [1] and it's in -next today. You can reuse that if you
>> are planning to target this for v4.11 or just use open coding in your
>> driver for v4.10 and target this move for v4.11 to avoid cross tree
>> dependencies as I already mentioned in your previous thread.
>
> I dont have your original patch in my mailbox, but I wonder if
> returning a pointer to property string for a node whose reference has
> already been released is safe to do? Probably not an issue for the root
> node, but still feels counter-intuitive.
>

I am not sure if I understand the issue here. Are you referring a case
where of_root is freed ?

Also I have seen drivers today just using this pointer directly, but
it's better to copy the string(I just saw this done in one case)

> This is the code for reference:
>
> +int of_machine_get_model_name(const char **model)
> +{
> +       int error;
> +
> +       if (!of_node_get(of_root))
> +               return -EINVAL;
> +
> +       error = of_property_read_string(of_root, "model", model);
> +       if (error)
> +               error = of_property_read_string_index(of_root, "compatible",
> +                                                     0, model);
> +       of_node_put(of_root);
> +
> +       return error;
> +}
> +EXPORT_SYMBOL(of_machine_get_model_name);
>
> Thanks,
> Sekhar
>

-- 
Regards,
Sudeep