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From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: device tree binding documentation outdated
Date: Fri, 4 Oct 2013 16:58:25 +0100	[thread overview]
Message-ID: <20131004155825.GO12758@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20131004154536.GB2734@S2101-09.ap.freescale.net>

On Fri, Oct 04, 2013 at 11:45:39PM +0800, Shawn Guo wrote:
> On Thu, Oct 03, 2013 at 12:49:11AM +0100, Russell King - ARM Linux wrote:
> > RGMII mode.
> > 
> > In current hardware, the phy has its own 25MHz crystal.  This provides
> > the phy with its clocks, and the phy itself contains a PLL, which it
> > uses to generate 125MHz.
> > 
> > The phy can be (and is) configured to generate this 125MHz clock on
> > the CLK_25M pin, which is connected to the IMX6 ENET_REF_CLK pad (V22
> > ball).
> > 
> > Hence, we have in DT:
> > 	MX6QDL_PAD_ENET_REF_CLK__ENET_TX_CLK
> > 
> > So far, so good. 
> > 
> > 
> > On current hardware, GPIO 16 is not connected to anything except some
> > 0402 resistor pads where the resistor is not fitted.  On future hardware,
> > the above crystal will be removed, and the appropriate 0402 resistor
> > placed to supply a clock provided on GPIO 16 to the phy.
> > 
> > Hence, to support both hardware configurations transparently, GPIO 16
> > should be configured to generate a 25MHz clock for use by the phy.
> 
> On AR8035 XTLI pin?  Here is what I read from AR8035 data sheet.
> 
> XTLI (Analog input signal): Crystal oscillator input. Requires a 27 pF
> capacitor to GND.  Support external 25 MHz, 1.2V swing clock input
> through this pin.
> 
> XTLO (Analog output signal): Crystal oscillator output; 27 pF to GND.
> 
> Will AR8035 just work if we provide a digital 25Mhz clock (from GPIO_16)
> on its XTLI pin?

Well, "Support external 25 MHz, 1.2V swing clock input through this pin."
suggests the answer is yes.  The characterists suggest that if the supplied
clock is within -0.3 to 0.15V for the low level, and 0.8 to 1.5V for the
high level, it should work.

  reply	other threads:[~2013-10-04 15:58 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-26 19:51 device tree binding documentation outdated Russell King - ARM Linux
2013-09-26 20:29 ` Fabio Estevam
2013-09-26 20:59   ` Russell King - ARM Linux
2013-09-26 23:10     ` Matt Sealey
2013-09-26 23:29       ` Russell King - ARM Linux
2013-09-26 23:48         ` Matt Sealey
2013-09-27 13:15         ` Jason Cooper
2013-09-27 17:05           ` Russell King - ARM Linux
2013-09-27 18:31             ` Russell King - ARM Linux
2013-09-27 18:52               ` Fabio Estevam
2013-09-27 20:16                 ` Matt Sealey
2013-09-27 20:43                   ` Russell King - ARM Linux
2013-09-26 23:25     ` Fabio Estevam
2013-09-27 12:13       ` Russell King - ARM Linux
2013-09-27 13:26         ` Shawn Guo
2013-09-27 15:19           ` Russell King - ARM Linux
2013-09-27 15:49             ` Russell King - ARM Linux
2013-09-27 16:52             ` Matt Sealey
2013-09-27 17:49               ` Russell King - ARM Linux
2013-09-27 18:33                 ` Matt Sealey
2013-09-27 19:05                   ` Russell King - ARM Linux
2013-09-27 19:41                     ` Matt Sealey
2013-09-27 19:48                       ` Matt Sealey
2013-09-27 20:21                         ` Russell King - ARM Linux
2013-09-28  8:38                           ` Russell King - ARM Linux
2013-09-29  6:13                             ` Shawn Guo
2013-09-29  6:23                               ` Duan Fugang-B38611
2013-09-29  6:35                                 ` Shawn Guo
2013-09-29  6:47                                   ` Duan Fugang-B38611
2013-10-02 19:33                               ` Russell King - ARM Linux
2013-10-02 23:49                                 ` Russell King - ARM Linux
2013-10-03  2:21                                   ` Fabio Estevam
2013-10-04 15:45                                   ` Shawn Guo
2013-10-04 15:58                                     ` Russell King - ARM Linux [this message]
2013-09-29  5:01                         ` Shawn Guo
2013-09-27 20:18                       ` Russell King - ARM Linux
2013-09-28  3:28                       ` Fabio Estevam
2013-09-26 21:35   ` Linus Walleij
2013-09-27  2:51     ` Shawn Guo
2013-09-27  8:45       ` Russell King - ARM Linux
2013-09-27 12:28         ` Shawn Guo
2013-09-27 13:12           ` Jason Cooper
2013-09-27 13:21             ` Russell King - ARM Linux
2013-09-27 13:29               ` Linus Walleij
2013-09-27 13:31               ` Jason Cooper
2013-09-27 16:33                 ` Matt Sealey
2013-09-27 20:52                   ` Russell King - ARM Linux
2013-09-27 13:52               ` Arnaud Patard (Rtp)
2013-09-27 15:40           ` Matt Sealey
2013-09-27  9:49 ` Russell King - ARM Linux
2013-09-27 12:08   ` Sascha Hauer

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