linux-kernel - Re: [PATCH] base: soc: Handle custom soc information sysfs entries

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Date:   Thu, 03 Oct 2019 11:17:39 -0700
From:   mnalajal@...eaurora.org
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     rafael@...nel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, bjorn.andersson@...aro.org
Subject: Re: [PATCH] base: soc: Handle custom soc information sysfs entries

On 2019-10-03 00:05, Greg KH wrote:
> On Wed, Oct 02, 2019 at 05:06:14PM -0700, Murali Nalajala wrote:
>> Soc framework exposed sysfs entries are not sufficient for some
>> of the h/w platforms. Currently there is no interface where soc
>> drivers can expose further information about their SoCs via soc
>> framework. This change address this limitation where clients can
>> pass their custom entries as attribute group and soc framework
>> would expose them as sysfs properties.
>> 
>> Signed-off-by: Murali Nalajala <mnalajal@...eaurora.org>
>> ---
>>  drivers/base/soc.c      | 26 ++++++++++++++++++--------
>>  include/linux/sys_soc.h |  1 +
>>  2 files changed, 19 insertions(+), 8 deletions(-)
> 
> Can you change a soc driver to use this?  I don't think that this patch
> works because:
> 
>> 
>> diff --git a/drivers/base/soc.c b/drivers/base/soc.c
>> index 7c0c5ca..ec70a58 100644
>> --- a/drivers/base/soc.c
>> +++ b/drivers/base/soc.c
>> @@ -15,6 +15,8 @@
>>  #include <linux/err.h>
>>  #include <linux/glob.h>
>> 
>> +#define NUM_ATTR_GROUPS 3
>> +
>>  static DEFINE_IDA(soc_ida);
>> 
>>  static ssize_t soc_info_get(struct device *dev,
>> @@ -104,11 +106,6 @@ static ssize_t soc_info_get(struct device *dev,
>>  	.is_visible = soc_attribute_mode,
>>  };
>> 
>> -static const struct attribute_group *soc_attr_groups[] = {
>> -	&soc_attr_group,
>> -	NULL,
>> -};
>> -
>>  static void soc_release(struct device *dev)
>>  {
>>  	struct soc_device *soc_dev = container_of(dev, struct soc_device, 
>> dev);
>> @@ -121,6 +118,7 @@ static void soc_release(struct device *dev)
>>  struct soc_device *soc_device_register(struct soc_device_attribute 
>> *soc_dev_attr)
>>  {
>>  	struct soc_device *soc_dev;
>> +	const struct attribute_group **soc_attr_groups = NULL;
>>  	int ret;
>> 
>>  	if (!soc_bus_type.p) {
>> @@ -136,10 +134,20 @@ struct soc_device *soc_device_register(struct 
>> soc_device_attribute *soc_dev_attr
>>  		goto out1;
>>  	}
>> 
>> +	soc_attr_groups = kzalloc(sizeof(*soc_attr_groups) *
>> +						NUM_ATTR_GROUPS, GFP_KERNEL);
>> +	if (!soc_attr_groups) {
>> +		ret = -ENOMEM;
>> +		goto out2;
>> +	}
>> +	soc_attr_groups[0] = &soc_attr_group;
>> +	soc_attr_groups[1] = soc_dev_attr->custom_attr_group;
>> +	soc_attr_groups[2] = NULL;
> 
> You set this, but never do anything with it that I can see.  What am I
> missing?
no, since i am using the "soc_attr_groups" name as it here you do not 
see the assignment below.
It is something like this soc_dev->dev.groups = soc_attr_groups;
> 
>> +
>>  	/* Fetch a unique (reclaimable) SOC ID. */
>>  	ret = ida_simple_get(&soc_ida, 0, 0, GFP_KERNEL);
>>  	if (ret < 0)
>> -		goto out2;
>> +		goto out3;
>>  	soc_dev->soc_dev_num = ret;
>> 
>>  	soc_dev->attr = soc_dev_attr;
>> @@ -151,14 +159,16 @@ struct soc_device *soc_device_register(struct 
>> soc_device_attribute *soc_dev_attr
>> 
>>  	ret = device_register(&soc_dev->dev);
>>  	if (ret)
>> -		goto out3;
>> +		goto out4;
>> 
>>  	return soc_dev;
>> 
>> -out3:
>> +out4:
>>  	ida_simple_remove(&soc_ida, soc_dev->soc_dev_num);
>>  	put_device(&soc_dev->dev);
>>  	soc_dev = NULL;
>> +out3:
>> +	kfree(soc_attr_groups);
>>  out2:
>>  	kfree(soc_dev);
>>  out1:
> 
> You don't free it when the soc is removed?
agree, will fix it in my next patch.
> 
> thanks,
> 
> greg k-h
These changes are verified at my side on SM8250 with mode static 
compilation and module.