Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
IronPort-SDR: gCNpke3e6SB3YvskM0uZMBXJfNVYz5y2hIhG4RMG99Nz27aWAwn/YjqpFD3P+iWtc3PCDES+oi
 T+nzmKWR6r0g==
IronPort-SDR: jQ5S4iO8mBHoBUGFUFbqLCye4VRHBbTzfry3odGoq4oSZv2cVmTs/VUczYKTJgJF0TMaPfAvOF
 XnS0sxdN8wrA==
Subject: Re: [RESEND PATCH v6 1/4] mfd: syscon: Add fwnode_to_regmap
To:     Lee Jones <lee.jones@linaro.org>
Cc:     linux-kernel@vger.kernel.org, kishon@ti.com,
        devicetree@vger.kernel.org, arnd@arndb.de, robh@kernel.org,
        andriy.shevchenko@intel.com, cheol.yong.kim@intel.com,
        chuanhua.lei@linux.intel.com, qi-ming.wu@intel.com,
        yixin.zhu@intel.com
References: <cover.1585889042.git.eswara.kota@linux.intel.com>
 <9c58aeb1561f28f302921d54aee75942545c4971.1585889042.git.eswara.kota@linux.intel.com>
 <20200417093551.GH2167633@dell>
From:   Dilip Kota <eswara.kota@linux.intel.com>
Message-ID: <d5b7eb87-7468-a1c4-bf19-d676c8e9c49d@linux.intel.com>
Date:   Tue, 21 Apr 2020 12:06:18 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101
 Thunderbird/68.6.0
MIME-Version: 1.0
In-Reply-To: <20200417093551.GH2167633@dell>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 4/17/2020 5:35 PM, Lee Jones wrote:
> On Mon, 06 Apr 2020, Dilip Kota wrote:
>
>> Traverse regmap handle entry from firmware node handle.
>>
>> Signed-off-by: Dilip Kota <eswara.kota@linux.intel.com>
>> ---
>> Changes on v5:
>>    No changes
>>    
>> Changes on v5:
>>    No changes
>>
>> Changes on v4:
>>    No changes
>>
>>   drivers/mfd/syscon.c       | 8 ++++++++
>>   include/linux/mfd/syscon.h | 6 ++++++
>>   2 files changed, 14 insertions(+)
>>
>> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
>> index 3a97816d0cba..e085c50816b9 100644
>> --- a/drivers/mfd/syscon.c
>> +++ b/drivers/mfd/syscon.c
>> @@ -178,6 +178,14 @@ struct regmap *device_node_to_regmap(struct device_node *np)
>>   }
>>   EXPORT_SYMBOL_GPL(device_node_to_regmap);
>>   
>> +struct regmap *fwnode_to_regmap(struct fwnode_handle *fwnode)
>> +{
>> +	struct device_node *np = to_of_node(fwnode);
> You are assuming that the fwnode was Device Tree pointer.
>
> The point of a fwnode is that it could be one of multiple types.
>
> What if it was a pointer to an ACPI property?
Yes, i missed to check in other perspective. Thanks for pointing it.
While going through the System control driver to address the query, i 
noticed that System Control
driver is talking with 'of' framework only. (No ACPI)

So, i think to add a defensive check and return error pointer if 
'to_of_node' returns NULL
As System control Driver cannot talk with ACPI, so fwnode_to_regmap() 
cannot talk and return error.

Or, the other option is removing the 'fwnode_to_regmap()' definition 
itself, to avoid confusion as fwnode can
point to 'OF', 'ACPI'or 'swnode'.

But, i feel return error for ACPI or oother, looks better because 
'device_node' has fwnode pointer. And provide description
in the header file, mentioning function is success for 'OF' and returns 
error for the rest.

Regards,
Dilip

>
>