Subject: Re: [PATCH v9 1/3] dt-binding: clock: ast2700: modify soc0/1 clock
define

On 26/02/2025 06:10, Ryan Chen wrote:

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Subject: Re: [PATCH v9 1/3] dt-binding: clock: ast2700: modify soc0/1
clock define

On 25/02/2025 10:49, Ryan Chen wrote:

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Subject: Re: [PATCH v9 1/3] dt-binding: clock: ast2700: modify
soc0/1 clock define

On 24/02/2025 10:55, Ryan Chen wrote:

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-remove redundant SOC0_CLK_UART_DIV13:
SOC0_CLK_UART_DIV13 is not use at clk-ast2700.c, the clock
source tree is uart clk src -> uart_div_table -> uart clk.

-Change SOC0_CLK_HPLL_DIV_AHB to SOC0_CLK_AHBMUX:
modify clock tree implement.
older CLK_AHB use mpll_div_ahb/hpll_div_ahb to be ahb clock

source.

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mpll->mpll_div_ahb
                  -> clk_ahb
hpll->hpll_div_ahb

I can barely understand it and from the pieces I got, it does not
explain need for ABI break.

#1. SCU0_CLK_UART_DIV13 is redundant, it does not impact ABI break

You did not explain how it does not impact. Clock was exported,
there was a user and now there is no clock. User stops working. ABI

break.

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Sorry, SCU0_CLK_UART_DIV13 was defined, but was never referenced in
any

upstream device trees.


That's incomplete definition of ABI

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Since there is no in-tree usage of `SCU0_CLK_UART_DIV13`, its
removal does

not cause an ABI break.


You ignored out of tree users. Please read carefully ABI docs.

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#2. Change SOC0_CLK_HPLL_DIV_AHB to SOC0_CLK_AHBMUX Older

implement

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where `mpll_div_ahb` and `hpll_div_ahb` were **hardcoded
dividers** for

AHB.

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In **the new approach (v8)**, I refactored the clock tree to clock tree.

I still cannot parse sentences like "refactoring A to A". It's
meaningless to

me.

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It should be ABI-safe change

No, you do not understand the ABI. You removed a clock ID, that's
the ABI change.

Otherwise explain how this is not changing ABI.

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Or you want to keep original SOC0_CLK_HPLL_DIV_AHB define and

then

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add

SOC0_CLK_AHBMUX.

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To be 1st patch, then 2n patch remove redundant

SOC0_CLK_HPLL_DIV_AHB?

If you break the ABI you need to clearly explain why. We have long
conversations and you still did not say why.

Sorry, my point will be following steps to avoid potential ABI
issues, I can modify the patch series as follows:
1. **Patch 1:** Add `SOC0_CLK_AHBMUX` without removing

`SOC0_CLK_HPLL_DIV_AHB`.

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2. **Patch 2:** Finally remove `SOC0_CLK_HPLL_DIV_AHB`.

I do not understand what changed here. You remove exported clock
which is ABI, so how is this answering my question.

You keep dodging my questions. Here I asked "why". I do not see any
answer why.

Apology, I can't catch your point. But I still need your guideline.

**Regarding `SCU0_CLK_UART_DIV13`:**
   - This clock ID was originally defined but was never used in any in-tree

device trees. (i2c-ast2700.c v1 ~ v9)

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   - So there should not have ABI-break am I correct?

No, because there are other users of bindings. All forks, out of tree DTS, other
projects etc. You defined ABI for them.

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**Regarding `SOC0_CLK_HPLL_DIV_AHB` → `SOC0_CLK_AHBMUX`:**
   - The previous implementation used dividers (`mpll_div_ahb`,
`hpll_div_ahb`) for AHB clock selection. (i2c-ast2700.c v1 ~ v8)
mpll->mpll_div_ahb
                  -> clk_ahb
hpll->hpll_div_ahb
   - The new approach use `SOC0_CLK_AHBMUX`, which AHB clock sources
via a mux. (i2c-ast2700.c v9)
mpll->
      ahb_mux -> div_table -> clk_ahb
hpll->

Your formatting is one of the problems I have troubles understanding it.
Above is not wrapped or wrapped oddly. You keep using bold * but double **,
which is not a standard markup. Please switch to standard mailing list
formatting - proper wrapping, only text mode and use client which actually can
parse and create that.

What I don't understand is how clocks could change in hardware. You described
implementation, but the clock IDS do not describe implementation but the the
mapping to real hardware clocks. So how SOC0_CLK_HPLL_DIV_AHB clock
disappeared from hardware?

Sorry, It's not disappeared, it is replaced by implement.

- The previous implementation hardcoded `mpll_div_ahb` and `hpll_div_ahb` as the only AHB clock sources:
     mpll -> mpll_div_ahb 
						-> clk_ahb
     hpll -> hpll_div_ahb> 

- The new approach introduces `SOC0_CLK_AHBMUX`, clear clock tree selection of AHB clock sources via a mux:
 Than through div_table to get ahb clk.
     mpll ->
       		-> ahb_mux -> div_table -> clk_ahb
     hpll ->

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   - And since i2c-ast2700.c (v8) is not applied, so there should also no one

use this ABI. Am I correct?

If binding was not applied, then what are you changing here?

My point is only i2c-ast2700.c (v8) used, which not be applied in Linux. 
And i2c-ast2700.c (v9) no need anymore.

Does it mean header described clock which was in the hardware but its
handling was not yet implemented in the driver?

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If this is not acceptable, my next patch will keep

SCU0_CLK_UART_DIV13/SCU0_CLK_HPLL_DIV_AHB define.

Maybe my last message was not clear, so: you need to explain why you are
breaking ABI and/or explain the ABI impact in the commit msg.

Understood your concern about this.
I think add new SCU0_CLK_AHBMUX to avoid ABI impact will be the better way.

Thank your guideline. 

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But add new SCU0_CLK_AHBMUX define for avoid your point ABI break. Is

this acceptable?


Best regards,
Krzysztof