[PATCH 5/9] drm/panthor: Implement support for multiple power domains

[Marek Vasut]

On 2/28/25 11:10 AM, Alexander Stein wrote:

Hi,

>> diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
>> index 51ee9cae94504..4348b7e917b64 100644
>> --- a/drivers/gpu/drm/panthor/panthor_device.c
>> +++ b/drivers/gpu/drm/panthor/panthor_device.c
>> @@ -75,6 +75,58 @@ static int panthor_reset_init(struct panthor_device *ptdev)
>>   	return 0;
>>   }
>>   
>> +/* Generic power domain handling code, see drivers/gpu/drm/tiny/simpledrm.c */
>> +static void panthor_detach_genpd(void *res)
>> +{
>> +	struct panthor_device *ptdev = res;
>> +	int i;
>> +
>> +	if (ptdev->pwr_dom_count <= 1)
>> +		return;
>> +
>> +	for (i = ptdev->pwr_dom_count - 1; i >= 0; i--)
>> +		dev_pm_domain_detach(ptdev->pwr_dom_devs[i], true);
>> +}
>> +
>> +static int panthor_genpd_init(struct panthor_device *ptdev)
>> +{
>> +	struct device *dev = ptdev->base.dev;
>> +	int i, ret;
>> +
>> +	ptdev->pwr_dom_count = of_count_phandle_with_args(dev->of_node, "power-domains",
>> +							  "#power-domain-cells");
>> +	/*
>> +	 * Single power-domain devices are handled by driver core nothing to do
>> +	 * here. The same for device nodes without "power-domains" property.
>> +	 */
>> +	if (ptdev->pwr_dom_count <= 1)
>> +		return 0;
>> +
>> +	if (ptdev->pwr_dom_count > ARRAY_SIZE(ptdev->pwr_dom_devs)) {
>> +		drm_warn(&ptdev->base, "Too many power domains (%d) for this device\n",
>> +			 ptdev->pwr_dom_count);
>> +		return -EINVAL;
>> +	}
>> +
>> +	for (i = 0; i < ptdev->pwr_dom_count; i++) {
>> +		ptdev->pwr_dom_devs[i] = dev_pm_domain_attach_by_id(dev, i);
>> +		if (!IS_ERR(ptdev->pwr_dom_devs[i]))
>> +			continue;
>> +
>> +		ret = PTR_ERR(ptdev->pwr_dom_devs[i]);
>> +		if (ret != -EPROBE_DEFER) {
>> +			drm_warn(&ptdev->base, "pm_domain_attach_by_id(%u) failed: %d\n", i, ret);
>> +			continue;
> 
> Is it a good idea to continue if a power-domain is missing? Any access might
> stuck completely. IMHO returning an error is more sensible.
> Also some dev_err_probe() should be added here.
Fixed both, thanks .