Re: [PATCH v6 15/15] xhci: tegra: Enable ELPG for runtime/system PM

Thierry Reding
2021-01-19T23:39:48Z

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On Tue, Jan 19, 2021 at 04:55:46PM +0800, JC Kuo wrote:
> This commit implements the complete programming sequence for ELPG
> entry and exit.
>
> 1. At ELPG entry, invokes tegra_xusb_padctl_enable_phy_sleepwalk()
> and tegra_xusb_padctl_enable_phy_wake() to configure XUSB PADCTL
> sleepwalk and wake detection circuits to maintain USB lines level
> and respond to wake events (wake-on-connect, wake-on-disconnect,
> device-initiated-wake).
>
> 2. At ELPG exit, invokes tegra_xusb_padctl_disable_phy_sleepwalk()
> and tegra_xusb_padctl_disable_phy_wake() to disarm sleepwalk and
> wake detection circuits.
>
> At runtime suspend, XUSB host controller can enter ELPG to reduce
> power consumption. When XUSB PADCTL wake detection circuit detects
> a wake event, an interrupt will be raised. xhci-tegra driver then
> will invoke pm_runtime_resume() for xhci-tegra.
>
> Runtime resume could also be triggered by protocol drivers, this is
> the host-initiated-wake event. At runtime resume, xhci-tegra driver
> brings XUSB host controller out of ELPG to handle the wake events.
>
> The same ELPG enter/exit procedure will be performed for system
> suspend/resume path so USB devices can remain connected across SC7.
>
> Signed-off-by: JC Kuo <jckuo@nvidia.com>
> ---
> v6:
> fix compiling warning: extra tokens at end of #ifdef directive
> v5:
> avoid using xhci_get_rhub()
> protect ELPG routines with (CONFIG_PM || CONFIG_PM_SLEEP)
> v4:
> reshuffle the code to avoid these pre-declarations
> v3:
> use 'unsigned int' for PHY index
> remove unnecessary 'else'
> drop IRQF_TRIGGER_HIGH when invokes devm_request_threaded_irq()
>
> drivers/usb/host/xhci-tegra.c | 407 ++++++++++++++++++++++++++++++----
> 1 file changed, 370 insertions(+), 37 deletions(-)

Acked-by: Thierry Reding <treding@nvidia.com>

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