Re: [PATCH] powerpc/powernv/flash: Check OPAL flash calls exist before using

[Vasant Hegde <hegdevasant@linux.vnet.ibm.com>]

On 9/15/21 11:53 AM, Michael Ellerman wrote:
> Vasant Hegde <hegdevasant@linux.vnet.ibm.com> writes:
>> Currently only FSP based powernv systems supports firmware update
>> interfaces. Hence check that the token OPAL_FLASH_VALIDATE exists
>> before initalising the flash driver.
>>
>> Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
>> ---
>>   arch/powerpc/platforms/powernv/opal-flash.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/powerpc/platforms/powernv/opal-flash.c b/arch/powerpc/platforms/powernv/opal-flash.c
>> index 7e7d38b17420..05490fc22fae 100644
>> --- a/arch/powerpc/platforms/powernv/opal-flash.c
>> +++ b/arch/powerpc/platforms/powernv/opal-flash.c
>> @@ -520,6 +520,10 @@ void __init opal_flash_update_init(void)
>>   {
>>   	int ret;
>>   
>> +	/* Firmware update is not supported by firmware */
>> +	if (!opal_check_token(OPAL_FLASH_VALIDATE))
>> +		return;
>> +
> 

Michael,

> That will mean the following files no longer appear on BMC systems:
> 
>    /sys/firmware/opal/image
>    /sys/firmware/opal/validate_flash
>    /sys/firmware/opal/manage_flash
>    /sys/firmware/opal/update_flash
> 
> Presumably those files don't actually work correctly, but are we sure
> their mere existence isn't used by anything at all?

That's correct. We never used these files/interfaces on BMC based systems.

> 
> We've had trouble in the past where removing sysfs files breaks tools
> unexpectedly, see smt_snooze_delay.

AFAIK only update_flash uses these interfaces on baremetal systems.
This change shouldn't break update_flash as these interfaces never used/worked
on BMC based powernv systems.

-Vasant