Re: [PATCH v14 03/10] power: reset: reboot-mode: Add support for 64 bit magic

[Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>]

On 8/28/2025 6:52 PM, Casey Connolly wrote:
> Hi Shivendra,
> 
> On 15/08/2025 16:35, Shivendra Pratap wrote:
>> Current reboot-mode supports a single 32-bit argument for any
>> supported mode. Some reboot-mode based drivers may require
>> passing two independent 32-bit arguments during a reboot
>> sequence, for uses-cases, where a mode requires an additional
>> argument. Such drivers may not be able to use the reboot-mode
>> driver. For example, ARM PSCI vendor-specific resets, need two
>> arguments for its operation – reset_type and cookie, to complete
>> the reset operation. If a driver wants to implement this
>> firmware-based reset, it cannot use reboot-mode framework.
>>
>> Introduce 64-bit magic values in reboot-mode driver to
>> accommodate dual 32-bit arguments when specified via device tree.
>> In cases, where no second argument is passed from device tree,
>> keep the upper 32-bit of magic un-changed(0) to maintain backward
>> compatibility.
> 
> How about adding a n_magic_args property to struct reboot_mode_driver?
> Then in struct mode_info change magic to be a u32 array of a fixed
> length (currently two in-keeping with the DT bindings).
> 
> Parsing the DT values then gets simpler (u32_array) and the magic value
> can be passed into the ->write() cb as a pointer since all the
> reboot_mode drivers already know how big the array is. Unpopulated DT
> values would just be 0.


sure. Will convert it to u32 magic[2] and ->write can now pass
"u32*" and can be de-referenced by the using driver.

Could not understand that how we want to use n_magic_args and who shall
set it? Do we statically define it to two for now? or should we skip
n_magic_args for now?

thanks,
Shivendra