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From: "David.Wu" <david.wu@rock-chips.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: heiko@sntech.de, dianders@chromium.org,
	andy.shevchenko@gmail.com, huangtao@rock-chips.com,
	hl@rock-chips.com, xjq@rock-chips.com, zyw@rock-chips.com,
	cf@rock-chips.com, linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-i2c@vger.kernel.org,
	linux-kernel@vger.kernel.org, David Wu <wdc@rock-chips.com>
Subject: Re: [PATCH v5 2/2] i2c: rk3x: add i2c support for rk3399 soc
Date: Fri, 15 Apr 2016 20:10:16 +0800	[thread overview]
Message-ID: <5710DA28.6010104@rock-chips.com> (raw)
In-Reply-To: <20160414184848.GB2338@katana>

Hi Wolfram,

在 2016/4/15 2:48, Wolfram Sang 写道:
>> + - input-clk-rate : frequency rate of function clock used(in Hz). If omitted,
>> +	the default clock rate is used. It is just used at rk3399 soc.
> Why is this needed? Why don't we simply use the default or calculate the
> best value somehow?
The default frequency rate of function clock is 50M Hz, it can match F/S 
mode,
but HS mode not. If use default rate 50M to get 1.7M scl-frequency rate 
, we could not
get accurately 1.7M frequecy rate. The input-clk-rate is more higher, we 
get more
accurately scl-frequency rate,  as 200M is a suitable input-clk-rate.

If 200M was used for F/S mode, it would increase power consumption, so 
add a option that
could be configured from DT.

>> + * @t_calc: Caculated rk3x private timings  that would
>> + * be written into regs
> double space
>

WARNING: multiple messages have this Message-ID (diff)
From: david.wu@rock-chips.com (David.Wu)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v5 2/2] i2c: rk3x: add i2c support for rk3399 soc
Date: Fri, 15 Apr 2016 20:10:16 +0800	[thread overview]
Message-ID: <5710DA28.6010104@rock-chips.com> (raw)
In-Reply-To: <20160414184848.GB2338@katana>

Hi Wolfram,

? 2016/4/15 2:48, Wolfram Sang ??:
>> + - input-clk-rate : frequency rate of function clock used(in Hz). If omitted,
>> +	the default clock rate is used. It is just used at rk3399 soc.
> Why is this needed? Why don't we simply use the default or calculate the
> best value somehow?
The default frequency rate of function clock is 50M Hz, it can match F/S 
mode,
but HS mode not. If use default rate 50M to get 1.7M scl-frequency rate 
, we could not
get accurately 1.7M frequecy rate. The input-clk-rate is more higher, we 
get more
accurately scl-frequency rate,  as 200M is a suitable input-clk-rate.

If 200M was used for F/S mode, it would increase power consumption, so 
add a option that
could be configured from DT.

>> + * @t_calc: Caculated rk3x private timings  that would
>> + * be written into regs
> double space
>

  parent reply	other threads:[~2016-04-15 12:10 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-16 16:57 [PATCH v5 0/2] updates for rk3399 i2c support David Wu
2016-03-16 16:57 ` David Wu
2016-03-16 16:57 ` [PATCH v5 1/2] i2c: rk3x: switch to i2c generic dt parsing David Wu
2016-03-16 16:57   ` David Wu
2016-04-14 18:39   ` Wolfram Sang
2016-04-14 18:39     ` Wolfram Sang
2016-03-16 16:57 ` [PATCH v5 2/2] i2c: rk3x: add i2c support for rk3399 soc David Wu
2016-03-16 16:57   ` David Wu
2016-04-14 18:48   ` Wolfram Sang
2016-04-14 18:48     ` Wolfram Sang
2016-04-15  7:31     ` Heiko Stübner
2016-04-15  7:31       ` Heiko Stübner
2016-04-15 12:12       ` David.Wu
2016-04-15 12:12         ` David.Wu
2016-04-15 12:10     ` David.Wu [this message]
2016-04-15 12:10       ` David.Wu
2016-04-15 17:58       ` Wolfram Sang
2016-04-15 17:58         ` Wolfram Sang
2016-04-18 13:15         ` David.Wu
2016-04-18 13:15           ` David.Wu
2016-04-15 12:17   ` Heiko Stübner
2016-04-15 12:17     ` Heiko Stübner
2016-04-19 13:55   ` [PATCH v6] " David Wu
2016-04-19 13:55     ` David Wu
2016-04-21 22:00     ` Andy Shevchenko
2016-04-21 22:00       ` Andy Shevchenko
2016-04-27 20:56     ` Doug Anderson
2016-04-27 20:56       ` Doug Anderson
2016-04-27 20:56       ` Doug Anderson
     [not found]       ` <572212AE.5060904@rock-chips.com>
2016-04-28 21:28         ` Doug Anderson
2016-04-28 21:28           ` Doug Anderson

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