linux-kernel - Re: [PATCH v7 01/14] clk: tegra: Add PLLE HW power sequencer control

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Date:   Mon, 08 Feb 2021 11:28:27 -0800
From:   Stephen Boyd <sboyd@...nel.org>
To:     JC Kuo <jckuo@...dia.com>, gregkh@...uxfoundation.org,
        jonathanh@...dia.com, kishon@...com, mturquette@...libre.com,
        robh@...nel.org, thierry.reding@...il.com
Cc:     linux-tegra@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        nkristam@...dia.com, linux-clk@...r.kernel.org,
        JC Kuo <jckuo@...dia.com>, Thierry Reding <treding@...dia.com>
Subject: Re: [PATCH v7 01/14] clk: tegra: Add PLLE HW power sequencer control

Quoting JC Kuo (2021-01-19 23:34:01)
> PLLE has a hardware power sequencer logic which is a state machine
> that can power on/off PLLE without any software intervention. The
> sequencer has two inputs, one from XUSB UPHY PLL and the other from
> SATA UPHY PLL. PLLE provides reference clock to XUSB and SATA UPHY
> PLLs. When both of the downstream PLLs are powered-off, PLLE hardware
> power sequencer will automatically power off PLLE for power saving.
> 
> XUSB and SATA UPHY PLLs also have their own hardware power sequencer
> logic. XUSB UPHY PLL is shared between XUSB SuperSpeed ports and PCIE
> controllers. The XUSB UPHY PLL hardware power sequencer has inputs
> from XUSB and PCIE. When all of the XUSB SuperSpeed ports and PCIE
> controllers are in low power state, XUSB UPHY PLL hardware power
> sequencer automatically power off PLL and flags idle to PLLE hardware
> power sequencer. Similar applies to SATA UPHY PLL.
> 
> PLLE hardware power sequencer has to be enabled after both downstream
> sequencers are enabled.
> 
> This commit adds two helper functions:
> 1. tegra210_plle_hw_sequence_start() for XUSB PADCTL driver to enable
>    PLLE hardware sequencer at proper time.
> 
> 2. tegra210_plle_hw_sequence_is_enabled() for XUSB PADCTL driver to
>    check whether PLLE hardware sequencer has been enabled or not.
> 
> Signed-off-by: JC Kuo <jckuo@...dia.com>
> Acked-by: Thierry Reding <treding@...dia.com>
> ---

Acked-by: Stephen Boyd <sboyd@...nel.org>