linux-kernel - Re: [PATCH] clk: imx: fix ahb clock mux 1

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Date:	Tue, 3 May 2016 18:50:21 +0800
From:	Dong Aisheng <dongas86@...il.com>
To:	Shawn Guo <shawnguo@...nel.org>
Cc:	Stefan Agner <stefan@...er.ch>, Anson Huang <b20788@...escale.com>,
	Adrian Alonso <aalonso@...escale.com>,
	Frank Li <Frank.Li@...escale.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kernel@...gutronix.de" <kernel@...gutronix.de>,
	linux-clk@...r.kernel.org,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] clk: imx: fix ahb clock mux 1

Hi Shawn,

On Tue, May 3, 2016 at 4:32 PM, Shawn Guo <shawnguo@...nel.org> wrote:
> On Thu, Apr 28, 2016 at 02:07:03PM -0700, Stefan Agner wrote:
>> The clock parent of the AHB root clock when using mux option 1
>> is the SYS PLL 270MHz clock. This is specified in  Table 5-11
>> Clock Root Table of the i.MX 7Dual Applications Processor
>> Reference Manual.
>>
>> While it could be a documentation error, the 270MHz parent is
>> also mentioned in the boot ROM configuration in Table 6-28: The
>> clock is by default at 135MHz due to a POST_PODF value of 1
>> (=> divider of 2).
>>
>> Signed-off-by: Stefan Agner <stefan@...er.ch>
>
> Anson, Frank,
>
> Can you guys confirm this change is correct?
>

I just checked the doc,
it's correct the parent should be SYS_PLL_PFD2(270Mhz).
It's a documentation error of early version and it's already fixed
in latest internal doc.

Regards
Dong Aisheng

> Shawn
>
>> ---
>> Hi Shawn,
>>
>> I did not found a clock which was based on this clock which I
>> could measure externally... But the change is backed by the
>> documentation.
>>
>> --
>> Stefan
>>
>>  drivers/clk/imx/clk-imx7d.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/clk/imx/clk-imx7d.c b/drivers/clk/imx/clk-imx7d.c
>> index 7912be8..5229968 100644
>> --- a/drivers/clk/imx/clk-imx7d.c
>> +++ b/drivers/clk/imx/clk-imx7d.c
>> @@ -56,7 +56,7 @@ static const char *nand_usdhc_bus_sel[] = { "osc", "pll_sys_pfd2_270m_clk",
>>       "pll_sys_pfd2_135m_clk", "pll_sys_pfd6_clk", "pll_enet_250m_clk",
>>       "pll_audio_main_clk", };
>>
>> -static const char *ahb_channel_sel[] = { "osc", "pll_sys_pfd2_135m_clk",
>> +static const char *ahb_channel_sel[] = { "osc", "pll_sys_pfd2_270m_clk",
>>       "pll_dram_533m_clk", "pll_sys_pfd0_392m_clk",
>>       "pll_enet_125m_clk", "pll_usb_main_clk", "pll_audio_main_clk",
>>       "pll_video_main_clk", };
>> --
>> 2.8.0
>>
>>
>
> _______________________________________________
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> linux-arm-kernel@...ts.infradead.org
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