Re: [PATCH v1 07/12] scsi: ufs: add option to change default UFS power management level
From: Rob Herring
Date: Tue Dec 13 2016 - 15:05:16 EST
On Mon, Dec 12, 2016 at 04:54:20PM -0800, Subhash Jadavani wrote:
> UFS device and link can be put in multiple different low power modes hence
> UFS driver supports multiple different low power modes. By default UFS
> driver selects the default (optimal) low power mode (which gives moderate
> power savings and have relatively less enter and exit latencies) but
> we might have to tune this default power mode for different chipset
> platforms to meet the low power requirements/goals. Hence this patch
> adds option to change default UFS low power mode (level).
> Reviewed-by: Yaniv Gardi <ygardi@xxxxxxxxxxxxxx>
> Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
> .../devicetree/bindings/ufs/ufshcd-pltfrm.txt | 10 ++++++
> drivers/scsi/ufs/ufshcd-pltfrm.c | 14 ++++++++
> drivers/scsi/ufs/ufshcd.c | 39 ++++++++++++++++++++++
> drivers/scsi/ufs/ufshcd.h | 4 +--
> 4 files changed, 65 insertions(+), 2 deletions(-)
> diff --git a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> index a99ed55..c3836c5 100644
> --- a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> +++ b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> @@ -41,6 +41,14 @@ Optional properties:
> -lanes-per-direction : number of lanes available per direction - either 1 or 2.
> Note that it is assume same number of lanes is used both
> directions at once. If not specified, default is 2 lanes per direction.
> +- rpm-level : UFS Runtime power management level. Following PM levels are supported:
> + 0 - Both UFS device and Link in active state (Highest power consumption)
> + 1 - UFS device in active state but Link in Hibern8 state
> + 2 - UFS device in Sleep state but Link in active state
> + 3 - UFS device in Sleep state and Link in hibern8 state (default PM level)
> + 4 - UFS device in Power-down state and Link in Hibern8 state
> + 5 - UFS device in Power-down state and Link in OFF state (Lowest power consumption)
> +- spm-level : UFS System power management level. Allowed PM levels are same as rpm-level.
This looks like you are putting policy for Linux into DT.
What I would expect to see here is disabling of states that don't work
due to some h/w limitation. Otherwise, it is a user decision for what
modes to go into. Also, I think link and device states should be