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

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Date:   Wed, 6 Dec 2017 12:06:01 -0800
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Loys Ollivier <lollivier@...libre.com>
Cc:     Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Jerome Brunet <jbrunet@...libre.com>
Subject: Re: [PATCH v2] firmware: qcom: scm: Fix incorrect of_node_put call
 in scm_init

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.

---8<----

diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index af4c75217ea6..440d8f796faa 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -626,23 +626,11 @@ static int __init qcom_scm_init(void)
 	int ret;
 
 	fw_np = of_find_node_by_name(NULL, "firmware");
-
 	if (!fw_np)
-		return -ENODEV;
-
-	np = of_find_matching_node(fw_np, qcom_scm_dt_match);
-
-	if (!np) {
-		of_node_put(fw_np);
-		return -ENODEV;
-	}
-
-	of_node_put(np);
+		return 0;
 
 	ret = of_platform_populate(fw_np, qcom_scm_dt_match, NULL, NULL);
-
 	of_node_put(fw_np);
-
 	if (ret)
 		return ret;
 

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