linux-kernel - Re: [PATCH] base: soc: set machine name in soc_device

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Date:   Fri, 17 Mar 2023 10:25:50 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] base: soc: set machine name in soc_device_register if
 empty

On 17.03.2023 06:08, Greg Kroah-Hartman wrote:
> On Thu, Mar 16, 2023 at 09:35:59PM +0100, Heiner Kallweit wrote:
>> Several SoC drivers use the same of-based mechanism to populate the machine
>> name. Therefore move this to the core and try to populate the machine name
>> in soc_device_register if it's not set yet.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
>> ---
>>  drivers/base/soc.c | 15 +++++++++++++++
>>  1 file changed, 15 insertions(+)
>>
>> diff --git a/drivers/base/soc.c b/drivers/base/soc.c
>> index 0fb1d4ab9..8dec5228f 100644
>> --- a/drivers/base/soc.c
>> +++ b/drivers/base/soc.c
>> @@ -7,6 +7,7 @@
>>  
>>  #include <linux/sysfs.h>
>>  #include <linux/init.h>
>> +#include <linux/of.h>
>>  #include <linux/stat.h>
>>  #include <linux/slab.h>
>>  #include <linux/idr.h>
>> @@ -110,6 +111,18 @@ static void soc_release(struct device *dev)
>>  	kfree(soc_dev);
>>  }
>>  
>> +static void soc_device_set_machine(struct soc_device_attribute *soc_dev_attr)
>> +{
>> +	struct device_node *np;
>> +
>> +	if (soc_dev_attr->machine)
>> +		return;
>> +
>> +	np = of_find_node_by_path("/");
>> +	of_property_read_string(np, "model", &soc_dev_attr->machine);
>> +	of_node_put(np);
>> +}
>> +
>>  static struct soc_device_attribute *early_soc_dev_attr;
>>  
>>  struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr)
>> @@ -118,6 +131,8 @@ struct soc_device *soc_device_register(struct soc_device_attribute *soc_dev_attr
>>  	const struct attribute_group **soc_attr_groups;
>>  	int ret;
>>  
>> +	soc_device_set_machine(soc_dev_attr);
>> +
> 
> Does this mean some SoC drivers should also be changed at the same time
> if they are trying to do this?
> 
The then duplicated code can be removed from SoC drivers afterwards.
There's no need to do it at the same time.
This change just adds a fallback in case the SoC driver doesn't set "machine".
Means if a SoC driver populates machine differently, then this is respected
and not overwritten.

> And is "model" the correct of property for this?  I thought that devices
> also had "model" as a valid entry, is this documented somewhere in the
> DTS schema that I couldn't find?
> 

"model" is used by basically all SoC drivers for this purpose, a quick grep reveals:

drivers/soc/samsung/exynos-chipid.c:    of_property_read_string(root, "model", &soc_dev_attr->machine);
drivers/soc/fsl/guts.c: if (of_property_read_string(of_root, "model", &machine))
drivers/soc/amlogic/meson-mx-socinfo.c: of_property_read_string(np, "model", &soc_dev_attr->machine);
drivers/soc/amlogic/meson-gx-socinfo.c: of_property_read_string(np, "model", &soc_dev_attr->machine);
drivers/soc/aspeed/aspeed-socinfo.c:    of_property_read_string(np, "model", &machine);
drivers/soc/ti/k3-socinfo.c:    of_property_read_string(node, "model", &soc_dev_attr->machine);
drivers/soc/loongson/loongson2_guts.c:  if (of_property_read_string(root, "model", &machine))
drivers/soc/renesas/renesas-soc.c:      of_property_read_string(np, "model", &soc_dev_attr->machine);
drivers/soc/imx/soc-imx.c:      ret = of_property_read_string(root, "model", &soc_dev_attr->machine);
drivers/soc/imx/soc-imx8m.c:    ret = of_property_read_string(of_root, "model", &soc_dev_attr->machine);

Some don't set machine at all.

> thanks,
> 
> greg k-h

Heiner