linux-kernel - Re: [PATCH v2 11/12] usb: host: xhci-tegra: unlink power domain devices

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Message-ID: <a05503a2-f904-d3ca-fb79-31e97f8e6630@nvidia.com>
Date:   Tue, 8 Sep 2020 10:19:16 +0800
From:   JC Kuo <jckuo@...dia.com>
To:     Thierry Reding <thierry.reding@...il.com>
CC:     <gregkh@...uxfoundation.org>, <robh@...nel.org>,
        <jonathanh@...dia.com>, <kishon@...com>,
        <linux-tegra@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <nkristam@...dia.com>
Subject: Re: [PATCH v2 11/12] usb: host: xhci-tegra: unlink power domain
 devices

On 8/31/20 8:42 PM, Thierry Reding wrote:
> On Mon, Aug 31, 2020 at 12:40:42PM +0800, JC Kuo wrote:
>> This commit unlinks xhci-tegra platform device with ss/host power
>> domain devices. Reasons for this change is - at elpg entry, phy
>> sleepwalk and wake configuration need to be done before powering
>> down ss/host partitions, and phy need be powered off after powering
>> down ss/host partitions. Sequence looks like roughly below:
>>
>>   tegra_xusb_enter_elpg() -> xhci_suspend()
>>                           -> enable phy sleepwalk and wake if needed
>>                           -> power down ss/host partitions
>>                           -> power down phy
>>
>> If ss/host power domains are linked to xhci-tegra platform device, we
>> are not able to perform the sequence like above.
>>
>> This commit introduces:
>>   1. tegra_xusb_unpowergate_partitions() to power up ss and host
>>      partitions together. If ss/host power domain devices are
>>      available, it invokes pm_runtime_get_sync() to request power
>>      driver to power up partitions; If power domain devices are not
>>      available, tegra_powergate_sequence_power_up() will be used to
>>      power up partitions.
>>
>>   2. tegra_xusb_powergate_partitions() to power down ss and host
>>      partitions together. If ss/host power domain devices are
>>      available, it invokes pm_runtime_put_sync() to request power
>>      driver to power down partitions; If power domain devices are not
>>      available, tegra_powergate_power_off() will be used to power down
>>      partitions.
>>
>> Signed-off-by: JC Kuo <jckuo@...dia.com>
>> ---
>>  drivers/usb/host/xhci-tegra.c | 202 +++++++++++++++++++---------------
>>  1 file changed, 111 insertions(+), 91 deletions(-)
>>
>> diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
>> index 934be1686352..ce6526c2caf6 100644
>> --- a/drivers/usb/host/xhci-tegra.c
>> +++ b/drivers/usb/host/xhci-tegra.c
>> @@ -249,8 +249,6 @@ struct tegra_xusb {
>>  
>>  	struct device *genpd_dev_host;
>>  	struct device *genpd_dev_ss;
>> -	struct device_link *genpd_dl_host;
>> -	struct device_link *genpd_dl_ss;
>>  
>>  	struct phy **phys;
>>  	unsigned int num_phys;
>> @@ -814,36 +812,12 @@ static void tegra_xusb_phy_disable(struct tegra_xusb *tegra)
>>  
>>  static int tegra_xusb_runtime_suspend(struct device *dev)
>>  {
>> -	struct tegra_xusb *tegra = dev_get_drvdata(dev);
>> -
>> -	regulator_bulk_disable(tegra->soc->num_supplies, tegra->supplies);
>> -	tegra_xusb_clk_disable(tegra);
>> -
>>  	return 0;
>>  }
>>  
>>  static int tegra_xusb_runtime_resume(struct device *dev)
>>  {
>> -	struct tegra_xusb *tegra = dev_get_drvdata(dev);
>> -	int err;
>> -
>> -	err = tegra_xusb_clk_enable(tegra);
>> -	if (err) {
>> -		dev_err(dev, "failed to enable clocks: %d\n", err);
>> -		return err;
>> -	}
>> -
>> -	err = regulator_bulk_enable(tegra->soc->num_supplies, tegra->supplies);
>> -	if (err) {
>> -		dev_err(dev, "failed to enable regulators: %d\n", err);
>> -		goto disable_clk;
>> -	}
>> -
>>  	return 0;
>> -
>> -disable_clk:
>> -	tegra_xusb_clk_disable(tegra);
>> -	return err;
>>  }
>>  
>>  #ifdef CONFIG_PM_SLEEP
>> @@ -1019,10 +993,6 @@ static int tegra_xusb_load_firmware(struct tegra_xusb *tegra)
>>  static void tegra_xusb_powerdomain_remove(struct device *dev,
>>  					  struct tegra_xusb *tegra)
>>  {
>> -	if (tegra->genpd_dl_ss)
>> -		device_link_del(tegra->genpd_dl_ss);
>> -	if (tegra->genpd_dl_host)
>> -		device_link_del(tegra->genpd_dl_host);
>>  	if (!IS_ERR_OR_NULL(tegra->genpd_dev_ss))
>>  		dev_pm_domain_detach(tegra->genpd_dev_ss, true);
>>  	if (!IS_ERR_OR_NULL(tegra->genpd_dev_host))
>> @@ -1048,20 +1018,88 @@ static int tegra_xusb_powerdomain_init(struct device *dev,
>>  		return err;
>>  	}
>>  
>> -	tegra->genpd_dl_host = device_link_add(dev, tegra->genpd_dev_host,
>> -					       DL_FLAG_PM_RUNTIME |
>> -					       DL_FLAG_STATELESS);
>> -	if (!tegra->genpd_dl_host) {
>> -		dev_err(dev, "adding host device link failed!\n");
>> -		return -ENODEV;
>> +	return 0;
>> +}
>> +
>> +static int tegra_xusb_unpowergate_partitions(struct tegra_xusb *tegra)
>> +{
>> +	struct device *dev = tegra->dev;
>> +	bool use_genpd;
>> +	int rc;
>> +
>> +	use_genpd = of_property_read_bool(dev->of_node, "power-domains");
> 
> I don't think that's technically correct. Just because a "power-domains"
> property exists in DT doesn't mean any power domains are necessarily
> attached to the device. I think you'll need to check for something like
> 
> 	if (dev->pm_domain)
> 
> here.
> 
Thanks Thierry. I will do so in the next revision.
> Thierry
>