linux-kernel - Re: [PATCH v3 1/2] clk: exynos5433: do not use CLK_IGNORE

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Date:	Mon, 4 Jul 2016 19:26:14 +0900
From:	Andi Shyti <andi@...zian.org>
To:	Sylwester Nawrocki <s.nawrocki@...sung.com>
Cc:	Andi Shyti <andi.shyti@...sung.com>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Jaehoon Chung <jh80.chung@...sung.com>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Kukjin Kim <kgene@...nel.org>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	linux-samsung-soc@...r.kernel.org, linux-clk@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Andi Shyti <andi@...zian.org>
Subject: Re: [PATCH v3 1/2] clk: exynos5433: do not use CLK_IGNORE_UNUSED for
 SPI clocks

Hi Sylwester,

> >  	GATE(CLK_SCLK_SPI1, "sclk_spi1", "sclk_spi1_peric", ENABLE_SCLK_PERIC,
> > -			4, CLK_IGNORE_UNUSED | CLK_SET_RATE_PARENT, 0),
> > +			4, CLK_IS_CRITICAL | CLK_SET_RATE_PARENT, 0),
> 
> As Tomasz pointed out, this should be addressed in the driver/dts,
> we shouldn't be patching board configurations into a per-SoC driver.
> Other boards may want to keep this clock disabled.

The single clock lines are not configured in the exynos5433 dts,
but in the drivers/clk/samsung/clk-exynos5433.c file and it's the
only place where we can set the flags.

> What is an exact problem here, are you perhaps testing suspend to RAM?
> I tested my sound support patches on top of v4.7-rc1 and everything
> seemed to work well, I didn't notice any issues with the audio codec
> which was the only slave on the SPI 1 bus.

Yes, because the audio codec is on SPI1 and its bus line
(spi_busclk0) is CLK_SCLK_SPI1_PERIC while the CLK_SCLK_SPI1 is
set as CLK_IGNORE_UNUSED.

> Doesn't it help when you specify CLK_SCLK_SPI1 as the second clock
> ("spi_busclk0") of the spi_1 bus controller instead of
> CLK_SCLK_SPI0_PERIC? CLK_SCLK_SPI0_PERIC seem to be parent of
> CLK_SCLK_SPI1 so the enable state would be propagated.

nope! :(

For some reasons, if you set in the DTS as spi_busclk0 the
CLK_SCLK_SPI1 from cmu_peric you get a synchronus abort in the
s3c64xx_spi_config (the first read performed on the device).

Andi