Re: [PATCH V2] pmdomain: tegra: Add support for multi-socket platforms

[Jon Hunter <jonathanh@nvidia.com>]

On 02/06/2026 12:59, Thierry Reding wrote:
> On Tue, Jun 02, 2026 at 09:39:59AM +0100, Jon Hunter wrote:
>> On multi-socket platforms each socket has its own BPMP that is
>> registered with the kernel. For such platforms prefix the NUMA ID for
>> each socket to the BPMP powergate name to ensure there is a unique name
>> for each power-domain. Note that we only add the NUMA ID for powergates
>> that return a valid name because an invalid name indicates that the
>> powergate ID is not supported.
>>
>> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
>> ---
>> Changes since V1:
>> - Use NUMA ID as a prefix and not a suffix for the powergate name.
>>
>>   drivers/pmdomain/tegra/powergate-bpmp.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/pmdomain/tegra/powergate-bpmp.c b/drivers/pmdomain/tegra/powergate-bpmp.c
>> index 8cde4f384846..5e869b0eb96e 100644
>> --- a/drivers/pmdomain/tegra/powergate-bpmp.c
>> +++ b/drivers/pmdomain/tegra/powergate-bpmp.c
>> @@ -137,6 +137,11 @@ static char *tegra_bpmp_powergate_get_name(struct tegra_bpmp *bpmp,
>>   	if (err < 0 || msg.rx.ret < 0)
>>   		return NULL;
>>   
>> +	if (response.get_name.name[0] != '\0' &&
>> +	    dev_to_node(bpmp->dev) != NUMA_NO_NODE)
>> +		return kasprintf(GFP_KERNEL, "%d-%s", dev_to_node(bpmp->dev),
>> +				 response.get_name.name);
>> +
>>   	return kstrdup(response.get_name.name, GFP_KERNEL);
> 
> Why are we not checking response.get_name.name for the empty string in
> the single socket case? Or the other way around: why is this important
> for multi-socket if it isn't for single socket?

Simply because we don't want to return a valid string such as '0-' or 
'1-' for the case where we received a NULL terminated string. The caller 
would interpret the name '0-' being valid when it is not.

> Looking at the caller of this function, it will check for this case
> itself, so I'm thinking we should rework that as part of this patch and
> simply return NULL early for both cases when name[0] == '\0'. That way
> the caller is simplified and we get a bit more consistency in this
> function. It is going to make for a slightly bigger diff, but I think
> overall it'd be an improvement.

Yes I agree that would be better and then just check for '\0' in one 
place. OK I will send an update.

Jon

-- 
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