Re: [PATCH V2] soc/tegra: pmc: Add reboot notifier

[Jon Hunter <jonathanh@nvidia.com>]

On 25/11/2021 04:33, Dmitry Osipenko wrote:
> 23.11.2021 14:11, Jon Hunter пишет:
>> The Tegra PMC driver implements a restart handler that supports Tegra
>> specific reboot commands such as placing the device into 'recovery' mode
>> in order to reprogram the platform. This is accomplished by setting the
>> appropriate bit in the PMC scratch0 register prior to rebooting the
>> platform.
>>
>> For Tegra platforms that support PSCI or EFI, the default Tegra restart
>> handler is not called and the PSCI or EFI restart handler is called
>> instead. Hence, for Tegra platforms that support PSCI or EFI, the Tegra
>> specific reboot commands do not currently work. Fix this by moving the
>> code that programs the PMC scratch0 register into a separate reboot
>> notifier that will always be called on reboot.
>>
>> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
>> ---
>> Changes since V1:
>> - Don't change the behaviour for writing scratch0 register when the
>>    notifier is called.
>>
>>   drivers/soc/tegra/pmc.c | 33 ++++++++++++++++++++++++++++++---
>>   1 file changed, 30 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
>> index 575d6d5b4294..bb2f39597823 100644
>> --- a/drivers/soc/tegra/pmc.c
>> +++ b/drivers/soc/tegra/pmc.c
>> @@ -1064,10 +1064,8 @@ int tegra_pmc_cpu_remove_clamping(unsigned int cpuid)
>>   	return tegra_powergate_remove_clamping(id);
>>   }
>>   
>> -static int tegra_pmc_restart_notify(struct notifier_block *this,
>> -				    unsigned long action, void *data)
>> +static void tegra_pmc_program_reboot_reason(const char *cmd)
>>   {
>> -	const char *cmd = data;
>>   	u32 value;
>>   
>>   	value = tegra_pmc_scratch_readl(pmc, pmc->soc->regs->scratch0);
>> @@ -1085,6 +1083,27 @@ static int tegra_pmc_restart_notify(struct notifier_block *this,
>>   	}
>>   
>>   	tegra_pmc_scratch_writel(pmc, value, pmc->soc->regs->scratch0);
>> +}
>> +
>> +static int tegra_pmc_reboot_notify(struct notifier_block *this,
>> +				   unsigned long action, void *data)
>> +{
>> +	if (action == SYS_RESTART)
>> +		tegra_pmc_program_reboot_reason(data);
>> +
>> +	return NOTIFY_DONE;
>> +}
>> +
>> +static struct notifier_block tegra_pmc_reboot_notifier = {
>> +	.notifier_call = tegra_pmc_reboot_notify,
>> +};
>> +
>> +static int tegra_pmc_restart_notify(struct notifier_block *this,
>> +				    unsigned long action, void *data)
>> +{
>> +	u32 value;
>> +
>> +	tegra_pmc_program_reboot_reason(data);
> 
> So the PMC reason is programmed twice now? First time by the reboot
> handler and second by the restart? Why?

That's an oversight. OK, thanks I will fix that in a V3.

> BTW, could you please always CC LKML or request to include linux-tegra
> ML onto lore? Tegra ML uses Gmane and it's unusable for development
> since all email addresses are mangled, the Gmane support told me that
> only Tegra ML admin can disable mangling, but I'm not sure who is it,
> maybe Stephen Warren?

I see linux-tegra here: https://lore.kernel.org/linux-tegra/

Jon

-- 
nvpublic