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

From: Tudor Ambarus <tudor.ambarus@linaro.org>
To: "Sam Protsenko" <semen.protsenko@linaro.org>,
	"André Draszik" <andre.draszik@linaro.org>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski@linaro.org>
Cc: peter.griffin@linaro.org, robh+dt@kernel.org,
	krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
	linux-kernel@vger.kernel.org, kernel-team@android.com,
	willmcvicker@google.com, alim.akhtar@samsung.com,
	s.nawrocki@samsung.com, tomasz.figa@gmail.com,
	cw00.choi@samsung.com, mturquette@baylibre.com, sboyd@kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-clk@vger.kernel.org,
	devicetree@vger.kernel.org
Subject: Re: [PATCH 3/5] arm64: dts: exynos: gs101: use correct clocks for usi8
Date: Mon, 29 Jan 2024 16:33:17 +0000	[thread overview]
Message-ID: <49d187f5-3c37-4c3b-a2f5-52dd805e84ee@linaro.org> (raw)
In-Reply-To: <b801e6b2-dfdf-4776-b90a-83780982b142@linaro.org>

On 1/27/24 04:00, Tudor Ambarus 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.

Andre' is right, I messed up the bus clocks for USI. I tested the IPCLK,
the one that feeds USI clients, but I failed to correctly test the bus
clock. I retested by removing the clk_ignore_unused bootargs param and
verified that the patch is correct.

Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Tested-by: Tudor Ambarus <tudor.ambarus@linaro.org>