linux-kernel - Re: [RESEND PATCH v1 2/4] dt-bindings: power: reset: Add alternate reboot mode format

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Message-ID: <a77491b3-3917-8380-cf94-a4e3ccbbf22c@codeaurora.org>
Date:   Wed, 26 Aug 2020 14:39:08 -0400
From:   Elliot Berman <eberman@...eaurora.org>
To:     Rob Herring <robh@...nel.org>, ebiggers@...gle.com,
        samitolvanen@...gle.com
Cc:     Sebastian Reichel <sre@...nel.org>,
        Andy Yan <andy.yan@...k-chips.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>, linux-pm@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Trilok Soni <tsoni@...eaurora.org>,
        Prasad Sodagudi <psodagud@...eaurora.org>
Subject: Re: [RESEND PATCH v1 2/4] dt-bindings: power: reset: Add alternate
 reboot mode format

On 8/25/2020 5:25 PM, Rob Herring wrote:
> On Tue, Aug 18, 2020 at 11:54:14AM -0700, Elliot Berman wrote:
>> Current reboot-mode device tree schema does not support reboot commands
>> with spaces in them [1]. Add an optional new node "reboot-mode-names"
>> and "reboot-mode-magic" which add an array of strings and u32s,
>> respectively which would permit any string in this framework.
> 
> Kind of a weak justification. The intent was for the names to be a key,
> not a multi word description which your example seems to be. Is
> "dm-verity device corrupted" something Android has already standardized
> on?

+Eric/Sami to comment further

I wonder if you're thinking it's better to change the kernel_restart in 
dm-verity-target.c?

Alternatively, I could respin so that spaces in the reboot cmd is 
replaced with "-" in reboot_mode_notify(). This way, there is no need to 
change dm-verity driver or change devicetree schema. i.e.:

@@ -44,9 +44,13 @@ static int reboot_mode_notify(struct notifier_block 
*this,
  {
         struct reboot_mode_driver *reboot;
         unsigned int magic;
+       char *reboot_cmd;
+
+       reboot_cmd = kstrdup(cmd, GFP_KERNEL);
+       strreplace(reboot_cmd, ' ', '-');

         reboot = container_of(this, struct reboot_mode_driver, 
reboot_notifier);
-       magic = get_reboot_mode_magic(reboot, cmd);
+       magic = get_reboot_mode_magic(reboot, reboot_cmd);
         if (magic)
                 reboot->write(reboot, magic);

> 
>>
>> [1]:
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/md/dm-verity-target.c?h=v5.5#n255
>>
>> Signed-off-by: Elliot Berman <eberman@...eaurora.org>
>> ---
>>   .../devicetree/bindings/power/reset/reboot-mode.yaml    | 17 +++++++++++++++++
>>   1 file changed, 17 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/power/reset/reboot-mode.yaml b/Documentation/devicetree/bindings/power/reset/reboot-mode.yaml
>> index a6c9102..4ea6b33 100644
>> --- a/Documentation/devicetree/bindings/power/reset/reboot-mode.yaml
>> +++ b/Documentation/devicetree/bindings/power/reset/reboot-mode.yaml
>> @@ -19,6 +19,9 @@ description: |
>>     the bootloader what to do when the system reboots, and should be named
>>     as mode-xxx = <magic> (xxx is mode name, magic should be a non-zero value).
>>   
>> +  reboot-mode-magic and reboot-mode-names may be used in addition/instead of
>> +  mode-xxx style.
> 
> It should be either/or in my opinion, not both.

OK, I can fix in the next patch.

> 
>> +
>>     For example, modes common Android platform are:
>>       - normal: Normal reboot mode, system reboot with command "reboot".
>>       - recovery: Android Recovery mode, it is a mode to format the device or update a new image.
>> @@ -32,6 +35,14 @@ properties:
>>         description: |
>>           Default value to set on a reboot if no command was provided.
>>   
>> +  reboot-mode-names:
>> +    $ref: /schemas/types.yaml#/definitions/string-array
>> +    description: List of reboot commands, paired with reboot-mode-magic by index
>> +
>> +  reboot-mode-magic:
> 
> 'reboot-modes' would align with normal patterns.

Ditto

> 
>> +    $ref: /schemas/types.yaml#/definitions/uint32-array
>> +    description: List of reboot magic, paired with reboot-mode-names by index
>> +
>>   patternProperties:
>>     "^mode-.*$":
>>       $ref: /schemas/types.yaml#/definitions/uint32
>> @@ -44,4 +55,10 @@ examples:
>>         mode-bootloader = <2>;
>>         mode-loader = <3>;
>>       };
>> +
>> +  - |
>> +    reboot-mode {
>> +      reboot-mode-names = "normal", "bootloader", "dm-verity device corrupted";
>> +      reboot-mode-magic = <0x0>, <0x1>, <0xf>;
>> +    };
>>   ...
>> -- 
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>> a Linux Foundation Collaborative Project
>>