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From: Tudor Ambarus <tudor.ambarus@linaro.org>
To: "Sam Protsenko" <semen.protsenko@linaro.org>,
	"김재원/JAEWON KIM" <jaewon02.kim@samsung.com>
Cc: krzysztof.kozlowski@linaro.org, s.nawrocki@samsung.com,
	cw00.choi@samsung.com, alim.akhtar@samsung.com,
	mturquette@baylibre.com, sboyd@kernel.org,
	peter.griffin@linaro.org, andre.draszik@linaro.org,
	linux-samsung-soc@vger.kernel.org, linux-clk@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, willmcvicker@google.com,
	kernel-team@android.com
Subject: Re: [PATCH 4/4] clk: samsung: exynos850: fix propagation of SPI IPCLK rate
Date: Fri, 22 Mar 2024 09:39:28 +0000	[thread overview]
Message-ID: <867158d7-0d98-4058-9c2e-6b573ec68516@linaro.org> (raw)
In-Reply-To: <CAPLW+4=jSr6ZsB7XekXsiUBm0SmVpVFnqpgjViuF3=HpT4gRAg@mail.gmail.com>

Hi, Sam!

On 3/1/24 00:13, Sam Protsenko wrote:
> I fail to see how this patch fixes anything. Instead it looks to me it
> replaces the (already) correctly implemented logic with incorrect one.

I opened another thread asking for feedback on whether it's safe to
re-parent the USI MUX to OSCCLK at run-time, find it here:
https://lore.kernel.org/linux-samsung-soc/71df1d6b-f40b-4896-a672-c5f0f526fb1f@linaro.org/T/#m588abb87eb5fd8817d71d06b94c91eb84928e06b

Jaewon came up with the idea on verifying what the downstream clock
driver does. I added some prints in the driver, and indeed the USI MUX
re-parents to OSCCLK on low SPI clock rates in the GS101 case.

Thus I'll respin this patch set fixing GS101 on low USI clock rates by
re-parenting the USI MUX to OSCCLK. I'll leave exynos850 out if I don't
hear back from you, but I think it deserves the same fix. Allowing SPI
to modify the clock rate of HSI2C/I3C at run-time is bad IMO.
Re-parenting the USI MUX to OSCCLK fixes this problem, HSI2C/I3C will no
longer be affected on low SPI clock rates.

Cheers,
ta

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  parent reply	other threads:[~2024-03-22  9:39 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-29 12:20 [PATCH 0/4] clk: samsung: introduce nMUX to reparent MUX clocks Tudor Ambarus
2024-02-29 12:20 ` [PATCH 1/4] clk: samsung: introduce nMUX for MUX clks that can reparented Tudor Ambarus
2024-02-29 12:20 ` [PATCH 2/4] clk: samsung: gs101: propagate PERIC1 USI SPI clock rate Tudor Ambarus
2024-02-29 12:20 ` [PATCH 3/4] clk: samsung: gs101: propagate PERIC0 " Tudor Ambarus
2024-02-29 12:20 ` [PATCH 4/4] clk: samsung: exynos850: fix propagation of SPI IPCLK rate Tudor Ambarus
2024-03-01  0:13   ` Sam Protsenko
2024-03-01 11:28     ` Tudor Ambarus
2024-03-22  9:39     ` Tudor Ambarus [this message]
2024-03-22 18:09       ` Sam Protsenko
2024-03-25  7:15         ` Tudor Ambarus

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