linux-kernel - Re: [PATCH] clk: imx6q: remove unsupported pll4_audio

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Message-ID: <6eeb02d8-62fe-6b2a-d265-b437a02ef8d1@nelint.com>
Date:   Mon, 11 Mar 2019 07:02:53 -0700
From:   Eric Nelson <eric@...int.com>
To:     Lucas Stach <l.stach@...gutronix.de>, linux-clk@...r.kernel.org
Cc:     anson.huang@....com, clement.peron@...ialet.com,
        colin.didier@...ialet.com, devicetree@...r.kernel.org,
        festevam@...il.com, kernel@...gutronix.de,
        linux-arm-kernel@...ts.infradead.org, linux-imx@....com,
        linux-kernel@...r.kernel.org, mark.rutland@....com,
        mturquette@...libre.com, robh+dt@...nel.org,
        s.hauer@...gutronix.de, sboyd@...nel.org, shawnguo@...nel.org,
        tiny.windzz@...il.com
Subject: Re: [PATCH] clk: imx6q: remove unsupported pll4_audio_div

Hi Lucas,

On 3/11/19 4:37 AM, Lucas Stach wrote:
> Hi Eric,
> 
> Am Sonntag, den 10.03.2019, 16:18 -0700 schrieb Eric Nelson:
>> The pll4_audio_div attempted to reflect one bit of a two-bit
>> divisor (AUDIO_DIV_LSB) in the CCM_ANALOG_MISC2 register.
>>
>> Unfortunately, this divisor is non-functional at least on the
>> latest silicon revisions and has been removed from the reference
>> manual.
>>
>> This is discussed in this NXP Community thread:
>>
>>      https://community.nxp.com/thread/462806
>>
>> Remove the definition of pll4_audio_div to reflect this and
>> reparent the ssi, cko1, and ESAI/ASRC/SPDIF clocks to the
>> pll4_post_div clock.
>>
>>> Signed-off-by: Eric Nelson <eric@...int.com>
>> ---
>>   drivers/clk/imx/clk-imx6q.c               |   7 +-
>>   include/dt-bindings/clock/imx6qdl-clock.h | 127 +++++++++++++++---------------
>>   2 files changed, 66 insertions(+), 68 deletions(-)
>>

<snip>

>>   
>> diff --git a/include/dt-bindings/clock/imx6qdl-clock.h b/include/dt-bindings/clock/imx6qdl-clock.h
>> index b3cef29..dea23a9 100644
>> --- a/include/dt-bindings/clock/imx6qdl-clock.h
>> +++ b/include/dt-bindings/clock/imx6qdl-clock.h
>> @@ -213,69 +213,68 @@
>>>   #define IMX6QDL_CLK_CKO2			200
>>>   #define IMX6QDL_CLK_CKO				201
>>>   #define IMX6QDL_CLK_VDOA			202
>>> -#define IMX6QDL_CLK_PLL4_AUDIO_DIV		203
>>> -#define IMX6QDL_CLK_LVDS1_SEL			204

<snip>

>>> +#define IMX6QDL_CLK_LVDS1_SEL			203
>>> +#define IMX6QDL_CLK_LVDS2_SEL			204
>>> +#define IMX6QDL_CLK_LVDS1_GATE			205

<snip>

> 
> You can not renumber the DT clock defines, as this breaks DT backward
> compatibility. You can however remove IMX6QDL_CLK_PLL4_AUDIO_DIV and
> leave a hole in the numbers, maybe with a comment about why it exists.
> 

Okay. I wasn't aware of this requirement, and I'll send a V2.

It will also make the patch much smaller!