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Date:   Tue, 12 Jun 2018 13:26:36 -0600
From:   Rob Herring <robh@kernel.org>
To:     Sayali Lokhande <sayalil@codeaurora.org>
Cc:     subhashj@codeaurora.org, cang@codeaurora.org,
        vivek.gautam@codeaurora.org, rnayak@codeaurora.org,
        vinholikatti@gmail.com, jejb@linux.vnet.ibm.com,
        martin.petersen@oracle.com, asutoshd@codeaurora.org,
        evgreen@chromium.org, linux-scsi@vger.kernel.org,
        Mark Rutland <mark.rutland@arm.com>,
        Mathieu Malaterre <malat@debian.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH V2 1/3] scsi: ufs: set the device reference clock setting
Message-ID: <20180612192636.GA31725@rob-hp-laptop>
References: <1528455990-24572-1-git-send-email-sayalil@codeaurora.org>
 <1528455990-24572-2-git-send-email-sayalil@codeaurora.org>
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On Fri, Jun 08, 2018 at 04:36:28PM +0530, Sayali Lokhande wrote:
> From: Subhash Jadavani <subhashj@codeaurora.org>
> 
> 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 <subhashj@codeaurora.org>
> Signed-off-by: Can Guo <cang@codeaurora.org>
> Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>
> ---
>  .../devicetree/bindings/ufs/ufshcd-pltfrm.txt      |  7 +++
>  drivers/scsi/ufs/ufs.h                             |  9 ++++
>  drivers/scsi/ufs/ufshcd-pltfrm.c                   | 24 ++++++++++
>  drivers/scsi/ufs/ufshcd.c                          | 52 ++++++++++++++++++++++
>  drivers/scsi/ufs/ufshcd.h                          |  1 +
>  5 files changed, 93 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> index c39dfef..4522434 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.

I must have misunderstood your last response. I thought you could handle 
things without DT. If not, my question remains.

Rob