linux-kernel - Re: [RFC PATCH 2/4] power: reset: reboot-mode: Wire reboot

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Date:   Tue, 25 Jul 2023 14:04:28 -0700
From:   Elliot Berman <quic_eberman@...cinc.com>
To:     Mukesh Ojha <quic_mojha@...cinc.com>,
        Mark Rutland <mark.rutland@....com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Sebastian Reichel <sre@...nel.org>
CC:     Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-pm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <kernel@...cinc.com>,
        "Satya Durga Srinivasu Prabhala" <quic_satyap@...cinc.com>,
        Melody Olvera <quic_molvera@...cinc.com>,
        Prasad Sodagudi <quic_psodagud@...cinc.com>
Subject: Re: [RFC PATCH 2/4] power: reset: reboot-mode: Wire reboot_mode enum
 to magic



On 7/25/2023 3:03 AM, Mukesh Ojha wrote:
> 
> 
> On 7/25/2023 4:00 AM, Elliot Berman wrote:
>> Allow the reboot mode type to be wired to magic.
>>
>> Signed-off-by: Elliot Berman <quic_eberman@...cinc.com>
>> ---
>>   drivers/power/reset/reboot-mode.c | 30 ++++++++++++++++++++++++++----
>>   1 file changed, 26 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/power/reset/reboot-mode.c 
>> b/drivers/power/reset/reboot-mode.c
>> index a646aefa041b..4ea97ccbaf51 100644
>> --- a/drivers/power/reset/reboot-mode.c
>> +++ b/drivers/power/reset/reboot-mode.c
>> @@ -22,12 +22,8 @@ struct mode_info {
>>   static bool get_reboot_mode_magic(struct reboot_mode_driver *reboot,
>>                         const char *cmd, unsigned int *magic)
>>   {
>> -    const char *normal = "normal";
>>       struct mode_info *info;
>> -    if (!cmd)
>> -        cmd = normal;
>> -
>>       list_for_each_entry(info, &reboot->head, list) {
>>           if (!strcmp(info->mode, cmd)) {
>>               *magic = info->magic;
>> @@ -45,6 +41,32 @@ static int reboot_mode_notify(struct notifier_block 
>> *this,
>>       unsigned int magic;
>>       reboot = container_of(this, struct reboot_mode_driver, 
>> reboot_notifier);
>> +
>> +    if (!cmd) {
>> +        switch (mode) {
> 
> IIUC, mode will be filled up with reboot_mode during restart
> notifier and not reboot notifiers ?
> 

Ah, you're correct. I should register a restart notifier and not use 
reboot mode framework. I'll follow similar bindings.

>> +        case REBOOT_COLD:
>> +            cmd = "cold";
>> +            break;
>> +        case REBOOT_WARM:
>> +            cmd = "warm";
>> +            break;
>> +        case REBOOT_HARD:
>> +            cmd = "hard";
>> +            break;
>> +        case REBOOT_SOFT:
>> +            cmd = "soft";
>> +            break;
>> +        case REBOOT_GPIO:
>> +            cmd = "gpio";
> 
> These strings are already there kernel/reboot.c
> Can it be reused ?
> 
> #define REBOOT_COLD_STR         "cold"
> #define REBOOT_WARM_STR         "warm"
> #define REBOOT_HARD_STR         "hard"
> #define REBOOT_SOFT_STR         "soft"
> #define REBOOT_GPIO_STR         "gpio"
> #define REBOOT_UNDEFINED_STR    "undefined"
> 
> 

One set of constants are "binding" for devicetree and the other is for 
sysfs. I think they should be kept separate.

>> +            break;
>> +        }
>> +        if (get_reboot_mode_magic(reboot, cmd, &magic)) {
> 
> Is info->mode is going to filled up with mode-cold, mode-warm and so
> on from DT to compare against cmd?
> 
> What if , cmd is not among the one above switch, NULL pointer during
> strcmp ?
> > -Mukesh
> 
>> +            reboot->write(reboot, magic);
>> +            return NOTIFY_DONE;
>> +        }
>> +        cmd = "normal";
>> +    }
>> +
>>       if (get_reboot_mode_magic(reboot, cmd, &magic))
>>           reboot->write(reboot, magic);