From: Jisheng Zhang <jszhang@marvell.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Wolfram Sang <wsa@the-dreams.de>,
Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
ijc+devicetree <ijc+devicetree@hellion.org.uk>,
Kumar Gala <galak@codeaurora.org>,
Jarkko Nikula <jarkko.nikula@linux.intel.com>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
<linux-i2c@vger.kernel.org>,
devicetree <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] i2c: designware-platdrv: get fast/std speed scl high/low count from DT
Date: Wed, 13 Apr 2016 20:16:37 +0800 [thread overview]
Message-ID: <20160413201637.284a3673@xhacker> (raw)
In-Reply-To: <CAHp75VcHNdAUeob2iR6U1HbUQzEccdjPy8ffuG4mB_=ZX7EokQ@mail.gmail.com>
Dear Andy,
On Thu, 7 Apr 2016 21:05:35 +0300 Andy Shevchenko wrote:
> On Wed, Apr 6, 2016 at 10:28 AM, Jisheng Zhang <jszhang@marvell.com> wrote:
> > Sometimes, it's convenient to define the scl's high/low count directly,
> > e.g HW people would do some measurement then directly give out the
> > optimum counts. Previously, we solved the sda falling time and scl
> > falling time by i2c_dw_scl_hcnt() and i2c_dw_scl_lcnt(), then put them
> > into dt, but what we really care isn't the sda/scl falling time.
> >
> > From another side, the dw_i2c_acpi_configure() on ACPI platform also
> > get hcnt/lcnt values rather than the sda/scl falling time from ACPI
> > method, we want similar feature for DT platforms.
> >
>
> Instead of duplicating some words maybe better to explicitly define
> two groups of parameters and one which supersedes the other.
I'm sorry, I can't catch your meaning. Could you please kindly give more
details? Or examples of "two groups of parameters"
Thanks,
Jisheng
>
> > Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> > ---
> > Documentation/devicetree/bindings/i2c/i2c-designware.txt | 16 ++++++++++++++++
> > drivers/i2c/busses/i2c-designware-platdrv.c | 8 ++++++++
> > 2 files changed, 24 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> > index fee26dc..05176fbf 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> > @@ -20,6 +20,22 @@ Optional properties :
> > - i2c-sda-falling-time-ns : should contain the SDA falling time in nanoseconds.
> > This value which is by default 300ns is used to compute the tHIGH period.
> >
> > + - i2c-ss-scl-high-count : should contain the standard speed i2c clock SCL high
> > + count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns
> > + will be ignored.
> > +
> > + - i2c-ss-scl-low-count : should contain the standard speed i2c clock SCL low
> > + count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns
> > + will be ignored.
> > +
> > + - i2c-fs-scl-high-count : should contain the fast speed i2c clock SCL high
> > + count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns
> > + will be ignored.
> > +
> > + - i2c-fs-scl-low-count : should contain the fast speed i2c clock SCL low
> > + count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns
> > + will be ignored.
> > +
> > Example :
> >
> > i2c@f0000 {
> > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> > index d656657..8739a60 100644
> > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > @@ -188,6 +188,14 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
> > &dev->scl_falling_time);
> > device_property_read_u32(&pdev->dev, "clock-frequency",
> > &clk_freq);
> > + device_property_read_u16(&pdev->dev, "i2c-ss-scl-high-count",
> > + &dev->ss_hcnt);
> > + device_property_read_u16(&pdev->dev, "i2c-ss-scl-low-count",
> > + &dev->ss_lcnt);
> > + device_property_read_u16(&pdev->dev, "i2c-fs-scl-high-count",
> > + &dev->fs_hcnt);
> > + device_property_read_u16(&pdev->dev, "i2c-fs-scl-low-count",
> > + &dev->fs_lcnt);
> > }
> >
> > if (has_acpi_companion(&pdev->dev))
> > --
> > 2.8.0.rc3
> >
>
>
>
next prev parent reply other threads:[~2016-04-13 12:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-06 7:28 [PATCH] i2c: designware-platdrv: get fast/std speed scl high/low count from DT Jisheng Zhang
2016-04-07 17:57 ` Rob Herring
2016-04-13 12:11 ` Jisheng Zhang
2016-04-24 20:39 ` Wolfram Sang
2016-04-07 18:05 ` Andy Shevchenko
2016-04-13 12:16 ` Jisheng Zhang [this message]
2016-04-13 13:23 ` Andy Shevchenko
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