linux-kernel - Re: [PATCH v4 8/8] phy: ufs-qcom: Refactor all init steps into phy

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Date:   Fri, 22 Feb 2019 12:28:26 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Andy Gross <andy.gross@...aro.org>,
        Evan Green <evgreen@...omium.org>,
        Kishon Vijay Abraham I <kishon@...com>
Cc:     Marc Gonzalez <marc.w.gonzalez@...e.fr>,
        Can Guo <cang@...eaurora.org>,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Douglas Anderson <dianders@...omium.org>,
        Asutosh Das <asutoshd@...eaurora.org>,
        Evan Green <evgreen@...omium.org>,
        Jeffrey Hugo <jhugo@...eaurora.org>,
        Arnd Bergmann <arnd@...db.de>, linux-scsi@...r.kernel.org,
        Grygorii Strashko <grygorii.strashko@...com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        linux-kernel@...r.kernel.org, Manu Gautam <mgautam@...eaurora.org>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Vinayak Holikatti <vinholikatti@...il.com>
Subject: Re: [PATCH v4 8/8] phy: ufs-qcom: Refactor all init steps into phy_poweron

Quoting Evan Green (2019-02-13 15:25:26)
> The phy code was using implicit sequencing between the PHY driver
> and the UFS driver to implement certain hardware requirements.
> Specifically, the PHY reset register in the UFS controller needs
> to be deasserted before serdes start occurs in the PHY.
> 
> Before this change, the code was doing this by utilizing the two
> phy callbacks, phy_init() and phy_poweron(), as "init step 1" and
> "init step 2", where the UFS driver would deassert reset between
> these two steps.
> 
> This makes it challenging to power off the regulators in suspend,
> as regulators are initialized in init, not in poweron(), but only
> poweroff() is called during suspend, not exit().
> 
> For UFS, move the actual firing up of the PHY to phy_poweron() and
> phy_poweroff() callbacks, rather than init()/exit(). UFS calls
> phy_poweroff() during suspend, so now all clocks and regulators for
> the phy can be powered down during suspend.
> 
> QMP is a little tricky because the PHY is also shared with PCIe and
> USB3, which have their own definitions for init() and poweron(). Rename
> the meaty functions to _enable() and _disable() to disentangle from the
> PHY core names, and then create two different ops structures: one for
> UFS and one for the other PHY types.
> 
> In phy-qcom-ufs, remove the 'is_powered_on' and 'is_started' guards,
> as the generic PHY code does the reference counting. The
> 14/20nm-specific init functions get collapsed into the generic power_on()
> function, with the addition of a calibrate() callback specific to 14/20nm.
> 
> Signed-off-by: Evan Green <evgreen@...omium.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@...omium.org>