linux-kernel - Re: [RFC PATCH 3.7.0-rc2] dt: match id-table before creating platform device

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Date:	Tue, 23 Oct 2012 08:15:59 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Srinivas KANDAGATLA <srinivas.kandagatla@...com>
CC:	grant.likely@...retlab.ca, devicetree-discuss@...ts.ozlabs.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 3.7.0-rc2] dt: match id-table before creating platform
 device

Adding lkml. DT patches should go to both lists.

On 10/23/2012 05:30 AM, Srinivas KANDAGATLA wrote:
> From: Srinivas Kandagatla <srinivas.kandagatla@...com>
> 
> As part of of_platform_populate call, the existing code iterates each
> child node and then creates a platform device for each child, however
> there is bug in the code which does not check the match table before
> creating the platform device. This might result creating two platfrom
> devices and also invoking driver probe twice, which is incorrect.
> 
> This patch moves a existing of_match_node check to start of the function
> to fix the bug, doing this way will return immediately without creating
> any datastructures if the child does not match the supplied match-table.
> 
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...com>
> ---
>  drivers/of/platform.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index b80891b..1aaa560 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -367,6 +367,9 @@ static int of_platform_bus_create(struct device_node *bus,
>  		return 0;
>  	}
>  
> +	if (!of_match_node(matches, bus))
> +		return 0;
> +

This is not right. This function is recursive and this change would
break that. Perhaps we could only call of_platform_device_create_pdata
if !of_match_node instead, but I'm not completely sure that would be the
right thing to do. There's also some historical things we have to
support which is why we have of_platform_populate and of_platform_bus_probe.

Rob

>  	auxdata = of_dev_lookup(lookup, bus);
>  	if (auxdata) {
>  		bus_id = auxdata->name;
> @@ -379,7 +382,7 @@ 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 0;
>  
>  	for_each_child_of_node(bus, child) {
> 

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