From: Rob Herring <robh@kernel.org>
To: sayali <sayalil@codeaurora.org>
Cc: Subhash Jadavani <subhashj@codeaurora.org>,
Can Guo <cang@codeaurora.org>,
Vivek Gautam <vivek.gautam@codeaurora.org>,
Rajendra Nayak <rnayak@codeaurora.org>,
Vinayak Holikatti <vinholikatti@gmail.com>,
"James E.J. Bottomley" <jejb@linux.vnet.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
asutoshd@codeaurora.org, Evan Green <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
Date: Thu, 14 Jun 2018 08:29:20 -0600 [thread overview]
Message-ID: <CAL_JsqLsdEGEjPo8yh5dGoGWTes41QxUiJ4NN0Q9qsgLBaTpjw@mail.gmail.com> (raw)
In-Reply-To: <000101d403d3$87210d20$95632760$@codeaurora.org>
On Thu, Jun 14, 2018 at 5:33 AM, sayali <sayalil@codeaurora.org> wrote:
> Comment inline.
>
> Thanks,
> Sayali
> -----Original Message-----
> From: Rob Herring [mailto:robh@kernel.org]
> Sent: Wednesday, June 13, 2018 12:57 AM
> 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
>
> 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.
> [Sayali]: Ref clk frequency setting could vary from
> platfrom-to-platform(vendor specific). Hence we need to pass it via DT.
> Currently in DT we do not set/mention any ref clk frequency
> parameter. Hence I have added one new DT entry to configure
> required ref clk freq.
The clocks property contains "ref_clk". Is that not the same clock?
Why can't you read what that frequency is? Or you need to be able to
change it to a specific frequency? These all look like typical
oscillator frequencies, so I wouldn't expect you could change them
(other than divide by 2 maybe).
Rob
next prev parent reply other threads:[~2018-06-14 14:29 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1528455990-24572-1-git-send-email-sayalil@codeaurora.org>
2018-06-08 11:06 ` [PATCH V2 1/3] scsi: ufs: set the device reference clock setting Sayali Lokhande
2018-06-08 12:01 ` Adrian Hunter
2018-06-12 19:26 ` Rob Herring
2018-06-14 11:33 ` sayali
2018-06-14 13:35 ` Bart Van Assche
2018-06-15 20:37 ` valdis.kletnieks
2018-06-15 20:42 ` Bart Van Assche
2018-06-15 20:53 ` valdis.kletnieks
2018-06-15 20:58 ` Bart Van Assche
2018-06-14 14:29 ` Rob Herring [this message]
2018-06-21 8:52 ` sayali
2018-07-03 18:04 ` Rob Herring
2018-07-04 13:36 ` Sayali Lokhande
2018-06-08 11:06 ` [PATCH V2 2/3] scsi: ufs: Add ufs provisioning support Sayali Lokhande
2018-06-08 11:06 ` [PATCH V2 3/3] scsi: ufs: Add sysfs support for ufs provision Sayali Lokhande
2018-06-09 7:24 ` Greg Kroah-Hartman
2018-06-14 11:52 ` sayali
2018-06-09 11:50 ` kbuild test robot
2018-06-09 11:50 ` [RFC PATCH] scsi: ufs: dev_attr_ufs_provision can be static kbuild test robot
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