Re: [PATCH v2 1/2] ARM: OMAP2+: only search for GPMC DT child nodes on probe

[Javier Martinez Canillas <javier.martinez@collabora.co.uk>]

On 04/17/2013 11:27 PM, Jon Hunter wrote:
> 
> On 04/17/2013 03:34 PM, Javier Martinez Canillas wrote:
>> The GPMC DT probe function use for_each_node_by_name() to search
>> child device nodes of the GPMC controller. But this function does
>> not use the GPMC device node as the root of the search and instead
>> search across the complete Device Tree.
>> 
>> This means that any device node on the DT that is using any of the
>> GPMC child nodes names searched for will be returned even if they
>> are not connected to the GPMC, making the gpmc_probe_xxx_child()
>> function to fail.
>> 
>> Fix this by using the GPMC device node as the search root so the
>> search will be restricted to its children.
>> 
>> Reported-by: Lars Poeschel <poeschel@lemonage.de>
>> Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
>> ---
>> 
>> Changes since v1 (suggested by Jon Hunter):
>>   - Split the search for GPMC child nodes and only warn if a
>>     child probe fails on two different patches
>>   - Don't probe all childs unnecesary if a previous matched
>> 
>>  arch/arm/mach-omap2/gpmc.c |   33 ++++++++++-----------------------
>>  1 files changed, 10 insertions(+), 23 deletions(-)
>> 
>> diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c
>> index ed946df..6166847 100644
>> --- a/arch/arm/mach-omap2/gpmc.c
>> +++ b/arch/arm/mach-omap2/gpmc.c
>> @@ -1520,32 +1520,19 @@ static int gpmc_probe_dt(struct platform_device *pdev)
>>  		return ret;
>>  	}
>>  
>> -	for_each_node_by_name(child, "nand") {
>> -		ret = gpmc_probe_nand_child(pdev, child);
>> -		if (ret < 0) {
>> -			of_node_put(child);
>> -			return ret;
>> -		}
>> -	}
>> +	for_each_child_of_node(pdev->dev.of_node, child) {
>>  
>> -	for_each_node_by_name(child, "onenand") {
>> -		ret = gpmc_probe_onenand_child(pdev, child);
>> -		if (ret < 0) {
>> -			of_node_put(child);
>> -			return ret;
>> -		}
>> -	}
>> +		if (!child->name)
>> +			continue;
>>  
>> -	for_each_node_by_name(child, "nor") {
>> -		ret = gpmc_probe_generic_child(pdev, child);
>> -		if (ret < 0) {
>> -			of_node_put(child);
>> -			return ret;
>> -		}
>> -	}
>> +		if (of_node_cmp(child->name, "nand") == 0)
>> +			ret = gpmc_probe_nand_child(pdev, child);
>> +		else if (of_node_cmp(child->name, "onenand") == 0)
>> +			ret = gpmc_probe_onenand_child(pdev, child);
>> +		else if (of_node_cmp(child->name, "ethernet") == 0 ||
>> +			 of_node_cmp(child->name, "nor") == 0)
>> +			ret = gpmc_probe_generic_child(pdev, child);
>>  
>> -	for_each_node_by_name(child, "ethernet") {
>> -		ret = gpmc_probe_generic_child(pdev, child);
>>  		if (ret < 0) {
> 
> I think that we need to make sure that "ret" is initialised to 0 at the
> beginning of the function. We should not have a case where the child

Hi Jon,

I didn't set ret  to 0 at the beginning of the function since it is assigned the
return value of a previous call to of_property_read_u32(). So ret should be 0
when execution reaches the for loop.

> name does not match but who knows. Actually that raises another point,
> should we have an "else" clause at the end that WARNs on
> "unknown/unsupported child" device?
>

Actually I thought about it when I was writing that patch and then I decided to
not add a WARN for that case since nothing really fail in that case.

I mean if we want to check that a DT is well formed then I think we will need to
add much more checks and I don't know if is worth it.

But I don't have a strong opinion on this so if you want I can add it an send a v3.

>>  			of_node_put(child);
>>  			return ret;
>> 
> 
> Otherwise looks great.
> 
> Cheers
> Jon
> 

Best regards,
Javier