linux-kernel - Re: [PATCH 2/4] of/platform: return error on of_platform_device_create

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Date:	Tue, 13 May 2014 10:56:03 -0700
From:	Olof Johansson <olof@...om.net>
To:	Rob Herring <robherring2@...il.com>
Cc:	Grant Likely <grant.likely@...aro.org>,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	"Ivan T. Ivanov" <iivanov@...sol.com>,
	Josh Cartwright <joshc@...eaurora.org>,
	Courtney Cavin <courtney.cavin@...ymobile.com>,
	Bjorn Andersson <bjorn@...o.se>,
	Frank Rowand <frowand.list@...il.com>,
	Rob Herring <robh@...nel.org>
Subject: Re: [PATCH 2/4] of/platform: return error on
 of_platform_device_create_pdata failure

On Wed, May 07, 2014 at 04:48:16PM -0500, Rob Herring wrote:
> From: Rob Herring <robh@...nel.org>
> 
> of_platform_populate does not return an error if creating the platform
> device fails. This means almost any error from driver core cannot be
> detected by the caller. Fix this.
> 
> Signed-off-by: Rob Herring <robh@...nel.org>
> ---
>  drivers/of/platform.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 404d1da..622aeb3 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -391,7 +391,9 @@ static int of_platform_bus_create(struct device_node *bus,
>  	}
>  
>  	dev = of_platform_device_create_pdata(bus, bus_id, platform_data, parent);
> -	if (!dev || !of_match_node(matches, bus))
> +	if (!dev)
> +		return -ENODEV;
> +	if (!of_match_node(matches, bus))
>  		return 0;
>  
>  	for_each_child_of_node(bus, child) {

This patch caused every single MMC driver to break on OF platforms, as far
as I can tell.  Reverting it on last night's -next seems to resolve it.

The problem seems to be that of_platform_populate() will bail on the
first device that fails this.

How did you test this code, Frank? On what platform? Practically all my
targets here failed to mount rootfs from eMMC or SD card...

Note that the below patch mostly undoes the original intent of letting an error
percolate up, since only the last rc value is actually returned. So I doubt
it's the right patch to pick up, but either this or a revert is needed right
now.


-Olof


>From f4cdc90a500a339e5b96ca06d108e1be7a808d76 Mon Sep 17 00:00:00 2001
From: Olof Johansson <olof@...om.net>
Date: Tue, 13 May 2014 10:51:30 -0700
Subject: [PATCH] of/platform: Don't abort of_platform_populate() early

52c75b64a374 ('of/platform: return error on
of_platform_device_create_pdata failure') starts returning ENODEV on
some calls now, and that will make of_platform_populate terminate the
loop. Be tolerant of that particlar error return value instead.

Fixes: 52c75b64a374 ('of/platform: return error on of_platform_device_create_pdata failure')
Cc: Frank Rowand <frank.rowand@...ymobile.com>
Signed-off-by: Olof Johansson <olof@...om.net>
---
 drivers/of/platform.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 8a6de3c..310de38 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -524,7 +524,7 @@ int of_platform_populate(struct device_node *root,
 
 	for_each_child_of_node(root, child) {
 		rc = of_platform_bus_create(child, matches, lookup, parent, true);
-		if (rc)
+		if (rc && rc != -ENODEV)
 			break;
 	}
 
-- 
1.7.10.4

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