linux-kernel - Re: [PATCH v2 07/14] mfd: zl3073x: Add components versions register defs

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Message-ID: <c0ef6dad-ce7e-401c-9ae1-42105fcbf9c4@redhat.com>
Date: Thu, 10 Apr 2025 10:26:58 +0200
From: Ivan Vecera <ivecera@...hat.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, netdev@...r.kernel.org
Cc: Vadim Fedorenko <vadim.fedorenko@...ux.dev>,
 Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>,
 Jiri Pirko <jiri@...nulli.us>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Prathosh Satish <Prathosh.Satish@...rochip.com>,
 Lee Jones <lee@...nel.org>, Kees Cook <kees@...nel.org>,
 Andy Shevchenko <andy@...nel.org>, Andrew Morton
 <akpm@...ux-foundation.org>, Michal Schmidt <mschmidt@...hat.com>,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2 07/14] mfd: zl3073x: Add components versions register
 defs

On 10. 04. 25 9:13 dop., Krzysztof Kozlowski wrote:
> On 09/04/2025 16:42, Ivan Vecera wrote:
>> Add register definitions for components versions and report them
>> during probe.
>>
>> Signed-off-by: Ivan Vecera <ivecera@...hat.com>
>> ---
>>   drivers/mfd/zl3073x-core.c | 36 ++++++++++++++++++++++++++++++++++++
>>   1 file changed, 36 insertions(+)
>>
>> diff --git a/drivers/mfd/zl3073x-core.c b/drivers/mfd/zl3073x-core.c
>> index f0d85f77a7a76..28f28d00da1cc 100644
>> --- a/drivers/mfd/zl3073x-core.c
>> +++ b/drivers/mfd/zl3073x-core.c
>> @@ -1,7 +1,9 @@
>>   // SPDX-License-Identifier: GPL-2.0-only
>>   
>>   #include <linux/array_size.h>
>> +#include <linux/bitfield.h>
>>   #include <linux/bits.h>
>> +#include <linux/cleanup.h>
>>   #include <linux/dev_printk.h>
>>   #include <linux/device.h>
>>   #include <linux/export.h>
>> @@ -13,6 +15,14 @@
>>   #include <net/devlink.h>
>>   #include "zl3073x.h"
>>   
>> +/*
>> + * Register Map Page 0, General
>> + */
>> +ZL3073X_REG16_DEF(id,			0x0001);
>> +ZL3073X_REG16_DEF(revision,		0x0003);
>> +ZL3073X_REG16_DEF(fw_ver,		0x0005);
>> +ZL3073X_REG32_DEF(custom_config_ver,	0x0007);
>> +
>>   /*
>>    * Regmap ranges
>>    */
>> @@ -196,7 +206,9 @@ static void zl3073x_devlink_unregister(void *ptr)
>>    */
>>   int zl3073x_dev_init(struct zl3073x_dev *zldev)
>>   {
>> +	u16 id, revision, fw_ver;
>>   	struct devlink *devlink;
>> +	u32 cfg_ver;
>>   	int rc;
>>   
>>   	rc = devm_mutex_init(zldev->dev, &zldev->lock);
>> @@ -205,6 +217,30 @@ int zl3073x_dev_init(struct zl3073x_dev *zldev)
>>   		return rc;
>>   	}
>>   
>> +	/* Take device lock */
> 
> What is a device lock? Why do you need to comment standard guards/mutexes?

Just to inform code reader, this is a section that accesses device 
registers that are protected by this zl3073x device lock.

>> +	scoped_guard(zl3073x, zldev) {
>> +		rc = zl3073x_read_id(zldev, &id);
>> +		if (rc)
>> +			return rc;
>> +		rc = zl3073x_read_revision(zldev, &revision);
>> +		if (rc)
>> +			return rc;
>> +		rc = zl3073x_read_fw_ver(zldev, &fw_ver);
>> +		if (rc)
>> +			return rc;
>> +		rc = zl3073x_read_custom_config_ver(zldev, &cfg_ver);
>> +		if (rc)
>> +			return rc;
>> +	}
> 
> Nothing improved here. Andrew comments are still valid and do not send
> v3 before the discussion is resolved.

I'm accessing device registers here and they are protected by the device 
lock. I have to take the lock, register access functions expect this by 
lockdep_assert.

>> +
>> +	dev_info(zldev->dev, "ChipID(%X), ChipRev(%X), FwVer(%u)\n",
>> +		 id, revision, fw_ver);
>> +	dev_info(zldev->dev, "Custom config version: %lu.%lu.%lu.%lu\n",
>> +		 FIELD_GET(GENMASK(31, 24), cfg_ver),
>> +		 FIELD_GET(GENMASK(23, 16), cfg_ver),
>> +		 FIELD_GET(GENMASK(15, 8), cfg_ver),
>> +		 FIELD_GET(GENMASK(7, 0), cfg_ver));
> 
> 
> Both should be dev_dbg. Your driver should be silent on success.

+1
will change.

>> +
>>   	devlink = priv_to_devlink(zldev);
>>   	devlink_register(devlink);
>>   
> 
> 
> Best regards,
> Krzysztof
>