From: Richard Cochran <richardcochran@gmail.com>
To: Grygorii Strashko <grygorii.strashko@ti.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>
Subject: Re: [PATCH 7/9] net: ethernet: ti: cpts: calc mult and shift from refclk freq
Date: Wed, 14 Sep 2016 16:22:11 +0200 [thread overview]
Message-ID: <20160914142210.GE28592@localhost.localdomain> (raw)
In-Reply-To: <20160914130231.3035-8-grygorii.strashko@ti.com>
On Wed, Sep 14, 2016 at 04:02:29PM +0300, Grygorii Strashko wrote:
> @@ -35,6 +33,8 @@ Optional properties:
> For example in dra72x-evm, pcf gpio has to be
> driven low so that cpsw slave 0 and phy data
> lines are connected via mux.
> +- cpts_clock_mult : Numerator to convert input clock ticks into nanoseconds
> +- cpts_clock_shift : Denominator to convert input clock ticks into nanoseconds
You should explain to the reader how these will be calculated when the
properties are missing.
> diff --git a/drivers/net/ethernet/ti/cpts.c b/drivers/net/ethernet/ti/cpts.c
> index ff8bb85..8046a21 100644
> --- a/drivers/net/ethernet/ti/cpts.c
> +++ b/drivers/net/ethernet/ti/cpts.c
> @@ -418,18 +418,60 @@ void cpts_unregister(struct cpts *cpts)
> clk_disable(cpts->refclk);
> }
>
> +static void cpts_calc_mult_shift(struct cpts *cpts)
> +{
> + u64 maxsec;
> + u32 freq;
> + u32 mult;
> + u32 shift;
> + u64 ns;
> + u64 frac;
Why so many new lines? This isn't good style. Please combine
variables of the same type into one line and sort the lists
alphabetically.
> + if (cpts->cc_mult || cpts->cc.shift)
> + return;
> +
> + freq = clk_get_rate(cpts->refclk);
> +
> + /* Calc the maximum number of seconds which we can run before
> + * wrapping around.
> + */
> + maxsec = cpts->cc.mask;
> + do_div(maxsec, freq);
> + if (!maxsec)
> + maxsec = 1;
> + else if (maxsec > 600 && cpts->cc.mask > UINT_MAX)
> + maxsec = 600;
> +
> + clocks_calc_mult_shift(&mult, &shift, freq, NSEC_PER_SEC, maxsec);
> +
> + cpts->cc_mult = mult;
> + cpts->cc.mult = mult;
> + cpts->cc.shift = shift;
> + /* Check calculations and inform if not precise */
Contrary to this comment, you are not making any kind of judgment
about whether the calculations are precise or not.
> + frac = 0;
> + ns = cyclecounter_cyc2ns(&cpts->cc, freq, cpts->cc.mask, &frac);
> +
> + dev_info(cpts->dev,
> + "CPTS: ref_clk_freq:%u calc_mult:%u calc_shift:%u error:%lld nsec/sec\n",
> + freq, cpts->cc_mult, cpts->cc.shift, (ns - NSEC_PER_SEC));
> +}
> +
Thanks,
Richard
next prev parent reply other threads:[~2016-09-14 14:22 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 [this message]
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
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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