linux-kernel - Re: [PATCH 2/3] watchdog: aspeed: Support variable number of reset mask registers

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Message-ID: <c5cab3a0-b17f-494b-b856-ebf2fb68db60@roeck-us.net>
Date: Tue, 7 Oct 2025 21:21:03 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Chin-Ting Kuo <chin-ting_kuo@...eedtech.com>,
 "wim@...ux-watchdog.org" <wim@...ux-watchdog.org>,
 "robh@...nel.org" <robh@...nel.org>, "krzk+dt@...nel.org"
 <krzk+dt@...nel.org>, "conor+dt@...nel.org" <conor+dt@...nel.org>,
 "joel@....id.au" <joel@....id.au>,
 "andrew@...econstruct.com.au" <andrew@...econstruct.com.au>,
 "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
 "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
 "linux-arm-kernel@...ts.infradead.org"
 <linux-arm-kernel@...ts.infradead.org>,
 "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 BMC-SW <BMC-SW@...eedtech.com>
Subject: Re: [PATCH 2/3] watchdog: aspeed: Support variable number of reset
 mask registers

On 10/7/25 20:29, Chin-Ting Kuo wrote:
> Hi Guenter,
> 
> Thanks for the quick review.
> 
>> -----Original Message-----
>> From: Guenter Roeck <groeck7@...il.com> On Behalf Of Guenter Roeck
>> Sent: Tuesday, October 7, 2025 10:55 PM
>> Subject: Re: [PATCH 2/3] watchdog: aspeed: Support variable number of reset
>> mask registers
>>
>> On 10/7/25 01:36, Chin-Ting Kuo wrote:
>>> Starting from the AST2600 platform, the SoC design has become more
>>> complex, with an increased number of reset mask registers.
>>> To support this, introduce a new field 'num_reset_masks' in the
>>> 'aspeed_wdt_config' structure to specify the number of reset mask
>>> registers per platform. This change removes the need for hardcoded
>>> platform-specific logic and improves scalability for future SoCs.
>>>
>>> Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@...eedtech.com>
>>> ---
>>>    drivers/watchdog/aspeed_wdt.c | 12 ++++++++----
>>>    1 file changed, 8 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/watchdog/aspeed_wdt.c
>>> b/drivers/watchdog/aspeed_wdt.c index 837e15701c0e..e15f70c5e416
>>> 100644
>>> --- a/drivers/watchdog/aspeed_wdt.c
>>> +++ b/drivers/watchdog/aspeed_wdt.c
>>> @@ -35,6 +35,7 @@ struct aspeed_wdt_config {
>>>    	u32 irq_shift;
>>>    	u32 irq_mask;
>>>    	struct aspeed_wdt_scu scu;
>>> +	u32 num_reset_masks;
>>>    };
>>>
>>>    struct aspeed_wdt {
>>> @@ -54,6 +55,7 @@ static const struct aspeed_wdt_config ast2400_config =
>> {
>>>    		.wdt_reset_mask = 0x1,
>>>    		.wdt_reset_mask_shift = 1,
>>>    	},
>>> +	.num_reset_masks = 1,
>>
>> Looking at this again: Why set it on ast2400 ?
>>
> 
> This should be removed for AST2400 platform. I will update it in the next patch version.
> 
>>>    };
>>>
>>>    static const struct aspeed_wdt_config ast2500_config = { @@ -66,6
>>> +68,7 @@ static const struct aspeed_wdt_config ast2500_config = {
>>>    		.wdt_reset_mask = 0x1,
>>>    		.wdt_reset_mask_shift = 2,
>>>    	},
>>> +	.num_reset_masks = 1,
>>>    };
>>>
>>>    static const struct aspeed_wdt_config ast2600_config = { @@ -78,6
>>> +81,7 @@ static const struct aspeed_wdt_config ast2600_config = {
>>>    		.wdt_reset_mask = 0xf,
>>>    		.wdt_reset_mask_shift = 16,
>>>    	},
>>> +	.num_reset_masks = 2,
>>>    };
>>>
>>>    static const struct of_device_id aspeed_wdt_of_table[] = { @@ -482,8
>>> +486,9 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
>>>    	if ((of_device_is_compatible(np, "aspeed,ast2500-wdt")) ||
>>>    		(of_device_is_compatible(np, "aspeed,ast2600-wdt"))) {
>>
>> ... because the code here only evaluates it if this is an ast2500 or ast2600.
>>
>> If num_reset_masks would be set to 0 for ast2400, the value could be used
>> here.
>>
>> 	if (wdt->cfg->num_reset_masks) {
>> 		...
>> 	}
>>
>> and it would not be necessary to add of_device_is_compatible() for new chips.
>>
> 
> This "if" conditional statement includes not only reset mask configuration but also pulse polarity and driving type of reset output signal.
> How about changing this "if" statement to the below one?
> 	if (!of_device_is_compatible(np, "aspeed,ast2400-wdt")) {
> 		...
> 	}
> It will also not need to add of_device_is_compatible() for new chips.
> 

Ok..

Thanks,
Guenter