Hi Rob, For UFS provisioning, all we need is ref_clk to be set to 19.2MHz before actual descriptor write happens. So I can actually avoid parsing it via DT and use REF_CLK_FREQ_19_2_MHZ from enum ref_clk_freq (which is already added in my current implementation).
Thanks, Sayali -----Original Message----- From: Rob Herring [mailto:[email protected]] Sent: Thursday, May 24, 2018 12:19 AM To: Sayali Lokhande <[email protected]> Cc: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Mark Rutland <[email protected]>; Mathieu Malaterre <[email protected]>; open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS <[email protected]>; open list <[email protected]> Subject: Re: [PATCH RFC 1/3] scsi: ufs: set the device reference clock setting On Tue, May 22, 2018 at 09:51:38AM +0530, Sayali Lokhande wrote: > From: Subhash Jadavani <[email protected]> > > UFS host supplies the reference clock to UFS device and UFS device > specification allows host to provide one of the 4 frequencies (19.2 > MHz, > 26 MHz, 38.4 MHz, 52 MHz) for reference clock. Host should set the > device reference clock frequency setting in the device based on what > frequency it is supplying to UFS device. > > Signed-off-by: Subhash Jadavani <[email protected]> > [[email protected]: Resolved trivial merge conflicts] > Signed-off-by: Can Guo <[email protected]> > Signed-off-by: Sayali Lokhande <[email protected]> > --- > .../devicetree/bindings/ufs/ufshcd-pltfrm.txt | 8 +++ > drivers/scsi/ufs/ufs.h | 9 ++++ > drivers/scsi/ufs/ufshcd-pltfrm.c | 20 ++++++++ > drivers/scsi/ufs/ufshcd.c | 60 ++++++++++++++++++++++ > drivers/scsi/ufs/ufshcd.h | 2 + > 5 files changed, 99 insertions(+) > > diff --git a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt > b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt > index c39dfef..ac94220 100644 > --- a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt > +++ b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt > @@ -41,6 +41,12 @@ 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. > +- dev-ref-clk-freq : Specify the device reference clock frequency, must be one of the following: > + 0: 19.2 MHz > + 1: 26 MHz > + 2: 38.4 MHz > + 3: 52 MHz > + Defaults to 26 MHz if not specified. You already have "ref_clk", can't you just read its frequency? Rob
