linux-kernel - Re: [PATCH 3/5] arm64: dts: exynos: gs101: use correct clocks for usi8

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Date: Sat, 27 Jan 2024 04:00:36 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Sam Protsenko <semen.protsenko@...aro.org>,
 André Draszik <andre.draszik@...aro.org>
Cc: peter.griffin@...aro.org, robh+dt@...nel.org,
 krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
 linux-kernel@...r.kernel.org, kernel-team@...roid.com,
 willmcvicker@...gle.com, alim.akhtar@...sung.com, s.nawrocki@...sung.com,
 tomasz.figa@...il.com, cw00.choi@...sung.com, mturquette@...libre.com,
 sboyd@...nel.org, linux-arm-kernel@...ts.infradead.org,
 linux-samsung-soc@...r.kernel.org, linux-clk@...r.kernel.org,
 devicetree@...r.kernel.org
Subject: Re: [PATCH 3/5] arm64: dts: exynos: gs101: use correct clocks for
 usi8



On 1/27/24 03:22, Sam Protsenko wrote:
> On Fri, Jan 26, 2024 at 6:37 PM André Draszik <andre.draszik@...aro.org> wrote:
>>
>> Wrong pclk clocks have been used in this usi8 instance here. For USI
>> and I2C, we need the ipclk and pclk, where pclk is the bus clock.
>> Without it, nothing can work.
> 
> Empty line is missing here?
> 
>> It is unclear what exactly is using USI8_USI_CLK, but it is not
>> required for the IP to be operational at this stage, while pclk is.
> 
> From [1] it looks like DIV_CLK_PERIC0_USI8_USI is a common parrent for
> these two leaf gate clocks:
>   1. GOUT_BLK_PERIC0_UID_RSTNSYNC_CLK_PERIC0_USI8_USI_IPCLKPORT_CLK
>   2. GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_7
> 
> So IIUC, you replace clock #1 with clock #2 in this patch? If so, I

No, GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_7 is already used by
IPCLK, the one that controls the clock frequency.

So I understand Andre' replaces a child of the USI8 with something else.

I don't think this works. We shall at least test it. I tested my usi8
patches with the eeprom that's populated on the battery connector. I'll
sync with Andre' offline and redo the tests on Monday.

> think that's a right move, because in my experience RSTNSYNC clocks
> shouldn't be used at all for consumer IP-cores. That's why I never
> added RSTNSYNC clocks in clk-exynos850 driver at all -- I only see
> them useful for store/restore ops during suspend/resume.
> 
> [1] https://android.googlesource.com/kernel/gs/+/refs/tags/android-12.0.0_r0.17/drivers/soc/google/cal-if/gs101/cmucal-node.c#2793
> 
>> This also brings the DT in line with the clock names expected by the
>> usi and i2c drivers.
>>
>> Update the DTSI accordingly.
>>
>> Fixes: 6d44d1a1fb62 ("arm64: dts: exynos: gs101: define USI8 with I2C configuration")
>> Signed-off-by: André Draszik <andre.draszik@...aro.org>
>> ---
> 
> Reviewed-by: Sam Protsenko <semen.protsenko@...aro.org>
> 
>>  arch/arm64/boot/dts/exynos/google/gs101.dtsi | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm64/boot/dts/exynos/google/gs101.dtsi b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>> index bc251e565be6..e5b665be2d62 100644
>> --- a/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>> +++ b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>> @@ -380,7 +380,7 @@ usi8: usi@...700c0 {
>>                         ranges;
>>                         #address-cells = <1>;
>>                         #size-cells = <1>;
>> -                       clocks = <&cmu_peric0 CLK_GOUT_PERIC0_CLK_PERIC0_USI8_USI_CLK>,
>> +                       clocks = <&cmu_peric0 CLK_GOUT_PERIC0_PERIC0_TOP0_PCLK_7>,
>>                                  <&cmu_peric0 CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_7>;
>>                         clock-names = "pclk", "ipclk";
>>                         samsung,sysreg = <&sysreg_peric0 0x101c>;
>> @@ -397,7 +397,7 @@ hsi2c_8: i2c@...70000 {
>>                                 pinctrl-names = "default";
>>                                 pinctrl-0 = <&hsi2c8_bus>;
>>                                 clocks = <&cmu_peric0 CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_7>,
>> -                                        <&cmu_peric0 CLK_GOUT_PERIC0_CLK_PERIC0_USI8_USI_CLK>;
>> +                                        <&cmu_peric0 CLK_GOUT_PERIC0_PERIC0_TOP0_PCLK_7>;
>>                                 clock-names = "hsi2c", "hsi2c_pclk";
>>                                 status = "disabled";
>>                         };
>> --
>> 2.43.0.429.g432eaa2c6b-goog
>>