Hi, On 21/03/19 10:47 PM, Evan Green wrote: > The goal with this series is to enable shutting off regulators that power > UFS during system suspend. > > In "the good life" version of this, we'd just disable the regulators > in phy_poweroff() and be done with it. Unfortunately, that's not symmetric, > as regulators are not enabled during phy_poweron(). Ok, so you might think > we could just move the regulator enable and anything else that needs to > come along into phy_poweron(), so that we can then undo it all in > phy_poweroff(). That's where things get tricky. > > The qcom-qmp-phy overloaded the phy_init() and phy_poweron() callbacks, > basically to mean "init phase 1" and "init phase 2". There are two phases > because they have this phy_reset bit outside of the phy (in the UFS > controller registers), and they need to make sure this bit is toggled at > specific points in the phy init sequence. So there's this implicit > sequence in the init dance between ufs-qcom.c and phy-qcom-qmp.c: > 1) ufs-qcom asserts the PHY reset bit. > 2) phy-qcom-qmp phy_init() does most of its initialization, but exits early. > 3) ufs-qcom deasserts the PHY reset bit. > 4) phy-qcom-qmp phy_poweron() finishes its initialization. > > This init dance is very difficult to follow in the code (since it's split > between two drivers and not spelled out well), and arguably represents a > deficiency in the hardware description of these devices. > > In this series I'm proposing tweaking the bindings for the Qualcomm > UFS controller and PHY. In it we expose a reset controller from the > UFS controller, that is then picked up and used from the PHY code. > With this, the phy code can be reorganized to complete its initialization > in a single function, removing the implicit two-phase overloading. > > Then I can move most of the phy initialization, including enabling > the regulators, into phy_poweron(). Now, when phy_poweroff() is called, > the phy actually powers off. This finally disables the regulators > and allows me to save power in system suspend. > > Because the UFS PHY reset bit is now toggled in the PHY, rather > than in ufs-qcom, this also percolated to all other PHYs using > ufs-qcom, which from what I can see is just 8996. > > I removed the calls to phy_poweroff() during clock gating. This > was originally dialing down a clock or two, while leaving the phy powered. > I've now changed the semantics of phy_poweroff() to, well, actually power off. > This works great for userlands that have set UFS's spm_lvl to 5 (off) like > I have, but maybe changes power consumption for devices that have spm_lvl > set to 3. I could try to use phy_init() and phy_poweron() as the two > different possible transitions (fully off, and clocks off respectively), > but I'm not sure if it actually matters, and I like the idea that > phy_poweroff() really does power the thing off. > > Also, I don't have an 8996 device to test. If someone is able to test this > out and perhaps point out any (hopefully obvious) bugs in the 8996 portion, > I'd be grateful. > > This patch is based atop phy-next. Merged the series except the dts patches. Thanks Kishon > > Changes in v5: > - Updated tags > > Changes in v4: > - Do reset_control_* unconditionally since null is handled (Stephen). > - Keep doing reset_control* unconditionally through refactor (Stephen). > > Changes in v3: > - Refactor to only expose the reset controller in one change (Stephen). > - Add period to comment (Stephen). > - Reset err to 0 in ignored error case (Stephen). > - Add include of reset-controller.h (Stephen) > - Refactored to move reset control in a single commit (Stephen) > - Use no_pcs_sw_reset as an indicator of UFS reset in qmp-phy (Stephen). > - Assign ret = PTR_ERR() earlier, for better reuse (Stephen). > - Refactor init => poweron for all PHYs and UFS in one step (Stephen) > > Changes in v2: > - Added resets to example (Stephen). > - Remove include of reset.h (Stephen) > - Fix error print of phy_power_on (Stephen) > - Comment for reset controller warnings on id != 0 (Stephen) > - Add static to ufs_qcom_reset_ops (Stephen). > - Use devm_* to get the reset (Stephen) > - Clear ufs_reset on error getting it > - Remove needless error print (Stephen) > - Use devm_ to get the reset (Stephen) > - Removed whitespace changes (Stephen) > > Evan Green (8): > dt-bindings: ufs: Add #reset-cells for Qualcomm controllers > dt-bindings: phy-qcom-qmp: Add UFS PHY reset > dt-bindings: phy: qcom-ufs: Add resets property > arm64: dts: sdm845: Add UFS PHY reset > arm64: dts: msm8996: Add UFS PHY reset controller > scsi: ufs: qcom: Expose the reset controller for PHY > phy: qcom: Utilize UFS reset controller > phy: ufs-qcom: Refactor all init steps into phy_poweron > > .../devicetree/bindings/phy/qcom-qmp-phy.txt | 6 +- > .../devicetree/bindings/ufs/ufs-qcom.txt | 5 +- > .../devicetree/bindings/ufs/ufshcd-pltfrm.txt | 3 + > arch/arm64/boot/dts/qcom/msm8996.dtsi | 4 +- > arch/arm64/boot/dts/qcom/sdm845.dtsi | 3 + > drivers/phy/qualcomm/phy-qcom-qmp.c | 112 +++++++++-------- > drivers/phy/qualcomm/phy-qcom-ufs-i.h | 5 +- > drivers/phy/qualcomm/phy-qcom-ufs-qmp-14nm.c | 25 +--- > drivers/phy/qualcomm/phy-qcom-ufs-qmp-20nm.c | 25 +--- > drivers/phy/qualcomm/phy-qcom-ufs.c | 57 ++++++--- > drivers/scsi/ufs/Kconfig | 1 + > drivers/scsi/ufs/ufs-qcom.c | 114 +++++++++++------- > drivers/scsi/ufs/ufs-qcom.h | 4 + > 13 files changed, 193 insertions(+), 171 deletions(-) >
