From: Grygorii Strashko <grygorii.strashko@ti.com>
To: Richard Cochran <richardcochran@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>, <netdev@vger.kernel.org>,
Mugunthan V N <mugunthanvnm@ti.com>, Sekhar Nori <nsekhar@ti.com>,
<linux-kernel@vger.kernel.org>, <linux-omap@vger.kernel.org>,
WingMan Kwok <w-kwok2@ti.com>,
John Stultz <john.stultz@linaro.org>
Subject: Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from refclk freq
Date: Thu, 15 Sep 2016 00:14:35 +0300 [thread overview]
Message-ID: <4d5308ae-02ea-e561-d190-350b994efef1@ti.com> (raw)
In-Reply-To: <20160914210332.GG12195@netboy>
On 09/15/2016 12:03 AM, Richard Cochran wrote:
> On Wed, Sep 14, 2016 at 11:47:46PM +0300, Grygorii Strashko wrote:
>> As I understand (and tested), clocks_calc_mult_shift() will
>> return max possible mult which can be used without overflow.
>
> Yes, BUT the returned values depends on the @maxsec input. As the
> kerneldec says,
>
> * Larger ranges may reduce the conversion accuracy by chosing smaller
> * mult and shift factors.
>
> In addition to that, frequency tuning by calculating a percentage of
> 'mult', and if 'mult' is small, then the tuning resolution is poor.
>
> So we don't want @maxsec as large as possible, but as small as
> possible.
>
Ok. So, will it work if maxsec will be ~= (maxsec / 2) + 1?
+ 1 to cover potential delays of overflow check work execution.
[...]
--
regards,
-grygorii
next prev parent reply other threads:[~2016-09-14 21:14 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-14 13:02 [PATCH 0/9] net: ethernet: ti: cpts: update and fixes Grygorii Strashko
2016-09-14 13:02 ` [PATCH 1/9] net: ethernet: ti: exclude cpts from build when disabled Grygorii Strashko
2016-09-14 13:02 ` [PATCH 2/9] net: ethernet: ti: cpsw: minimize direct access to struct cpts Grygorii Strashko
2016-09-14 13:02 ` [PATCH 3/9] net: ethernet: ti: cpts: rework initialization/deinitialization Grygorii Strashko
2016-09-14 13:52 ` Richard Cochran
2016-09-14 20:10 ` Grygorii Strashko
2016-09-14 20:32 ` Richard Cochran
2016-09-14 20:37 ` Grygorii Strashko
2016-09-14 20:52 ` Richard Cochran
2016-09-14 20:59 ` Grygorii Strashko
2016-09-15 8:13 ` Richard Cochran
2016-09-14 13:02 ` [PATCH 4/9] net: ethernet: ti: cpts: move dt props parsing to cpts driver Grygorii Strashko
2016-09-14 13:55 ` Richard Cochran
2016-09-14 19:45 ` Grygorii Strashko
2016-09-14 20:03 ` Richard Cochran
2016-09-14 13:02 ` [PATCH 5/9] net: ethernet: ti: cpts: add return value to tx and rx timestamp funcitons Grygorii Strashko
2016-09-14 14:00 ` Richard Cochran
2016-09-14 13:02 ` [PATCH 6/9] net: ethernet: ti: cpts: clean up event list if event pool is empty Grygorii Strashko
2016-09-14 14:14 ` Richard Cochran
2016-09-14 19:54 ` Grygorii Strashko
2016-09-14 13:02 ` [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from refclk freq Grygorii Strashko
2016-09-14 14:22 ` Richard Cochran
2016-09-14 19:59 ` Grygorii Strashko
2016-09-14 20:26 ` Richard Cochran
2016-09-14 20:47 ` Grygorii Strashko
2016-09-14 21:03 ` Richard Cochran
2016-09-14 21:14 ` Grygorii Strashko [this message]
2016-09-15 11:58 ` Richard Cochran
2016-09-15 13:49 ` Richard Cochran
2016-09-14 13:02 ` [PATCH 8/9] net: ethernet: ti: cpts: fix overflow check period Grygorii Strashko
2016-09-14 14:25 ` Richard Cochran
2016-09-14 20:03 ` Grygorii Strashko
2016-09-14 20:08 ` Richard Cochran
2016-09-14 20:23 ` Grygorii Strashko
2016-09-14 20:43 ` Richard Cochran
2016-09-14 20:48 ` Grygorii Strashko
2016-09-14 13:02 ` [PATCH 9/9] net: ethernet: ti: cpts: switch to readl/writel_relaxed() Grygorii Strashko
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