linux-kernel - Re: [PATCH v2] firmware: qcom: scm: Fix incorrect of_node_put call in scm

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Date:   Fri, 8 Dec 2017 09:04:49 -0800
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Loys Ollivier <lollivier@...libre.com>
Cc:     Jerome Forissier <jerome.forissier@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        David Brown <david.brown@...aro.org>,
        Andy Gross <andy.gross@...aro.org>, linux-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Jerome Brunet <jbrunet@...libre.com>,
        Jens Wiklander <jens.wiklander@...aro.org>
Subject: Re: [PATCH v2] firmware: qcom: scm: Fix incorrect of_node_put call
 in scm_init

On 12/07, Loys Ollivier wrote:
> 
> 
> On 07/12/2017 09:42, Jerome Forissier wrote:
> > 
> > 
> > On 12/06/2017 09:06 PM, Stephen Boyd wrote:
> >> On 12/06, Loys Ollivier wrote:
> >>> When using other platform architectures, in the init of the qcom_scm
> >>> driver, of_node_put is called on /firmware if no qcom dt is found.
> >>> This results in a kernel error: Bad of_node_put() on /firmware.
> >>>
> >>> The call to of_node_put from the qcom_scm init is unnecessary as
> >>> of_find_matching_node is calling it automatically.
> >>>
> >>> Remove this of_node_put().
> >>>
> >>> Fixes: d0f6fa7ba2d6 ("firmware: qcom: scm: Convert SCM to platform driver")
> >>> Signed-off-by: Loys Ollivier <lollivier@...libre.com>
> >>> ---
> >>
> >> This still looks wrong. Especially if of_find_matching_node() is
> >> going to look for siblings of the /firmware node for the
> >> compatible string for scm device. Why do we check at all? Can't
> >> we just delete this and let of_platform_populate() take care of
> >> it? BTW, OP-TEE driver seems to have a similar problem.
> > 
> > https://lkml.org/lkml/2017/11/29/230
> >
> Well, the patch I sent is a fix for a specific bug I am encountering.
> I tested the patch and it solves my problem. Stephen, your changes looks
> good but it's a change in the driver's behavior. Maybe it could be
> another patch ?

Sure. But there's another of_node_put(fw_np) in this function, so
why isn't that also removed? Assuming of_find_matching_node() is
calling of_node_put() on what's passed in, then the node is going
to get put twice in the "working" case.

Andy?

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