linux-kernel - Re: [PATCH v3 10/10] clk: samsung: exynos5433: Add CLK_IGNORE_UNUSED flag to prevent the hang for suspend-to-ram

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Date:	Tue, 28 Apr 2015 11:15:30 +0200
From:	Sylwester Nawrocki <s.nawrocki@...sung.com>
To:	Chanwoo Choi <cw00.choi@...sung.com>
Cc:	tomasz.figa@...il.com, mturquette@...aro.org, kgene@...nel.org,
	inki.dae@...sung.com, chanho61.park@...sung.com,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org, Jonghwa Lee <jonghwa3.lee@...sung.com>
Subject: Re: [PATCH v3 10/10] clk: samsung: exynos5433: Add CLK_IGNORE_UNUSED
 flag to prevent the hang for suspend-to-ram

Hi Chanwoo,

On 27/04/15 13:36, Chanwoo Choi wrote:
> From: Jonghwa Lee <jonghwa3.lee@...sung.com>
> 
> Some clocks are required being unmasked for suspend-to-ram. Otherwise,
> PMU (Power Management Unit) will stick and power line never down.
> 
> Signed-off-by: Jonghwa Lee <jonghwa3.lee@...sung.com>
> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
> ---

> @@ -1718,11 +1722,14 @@ static struct samsung_gate_clock peric_gate_clks[] __initdata = {
>  	GATE(CLK_SCLK_SPI0, "sclk_spi0", "sclk_spi0_peric", ENABLE_SCLK_PERIC,
>  			3, CLK_SET_RATE_PARENT, 0),
>  	GATE(CLK_SCLK_UART2, "sclk_uart2", "sclk_uart2_peric",
> -			ENABLE_SCLK_PERIC, 2, CLK_SET_RATE_PARENT, 0),
> +			ENABLE_SCLK_PERIC, 2,
> +			CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, 0),
>  	GATE(CLK_SCLK_UART1, "sclk_uart1", "sclk_uart1_peric",
> -			ENABLE_SCLK_PERIC, 1, CLK_SET_RATE_PARENT, 0),
> +			ENABLE_SCLK_PERIC, 1,
> +			CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, 0),
>  	GATE(CLK_SCLK_UART0, "sclk_uart0", "sclk_uart0_peric",
> -			ENABLE_SCLK_PERIC, 0, CLK_SET_RATE_PARENT, 0),
> +			ENABLE_SCLK_PERIC, 0,
> +			CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, 0),
>  };
>  
>  static struct samsung_cmu_info peric_cmu_info __initdata = {
> @@ -3025,7 +3032,7 @@ static struct samsung_gate_clock aud_gate_clks[] __initdata = {
>  
>  	/* ENABLE_SCLK_AUD0 */
>  	GATE(CLK_ATCLK_AUD, "atclk_aud", "div_atclk_aud", ENABLE_SCLK_AUD0,
> -			2, 0, 0),
> +			2, CLK_IGNORE_UNUSED, 0),
>  	GATE(CLK_PCLK_DBG_AUD, "pclk_dbg_aud", "div_pclk_dbg_aud",
>  			ENABLE_SCLK_AUD0, 1, 0, 0),
>  	GATE(CLK_SCLK_AUD_CA5, "sclk_aud_ca5", "div_aud_ca5", ENABLE_SCLK_AUD0,
> @@ -3425,9 +3432,11 @@ static struct samsung_gate_clock gscl_gate_clks[] __initdata = {
>  	GATE(CLK_ACLK_GSCLNP_111, "aclk_gsclnp_111", "mout_aclk_gscl_111_user",
>  			ENABLE_ACLK_GSCL, 6, CLK_IGNORE_UNUSED, 0),
>  	GATE(CLK_ACLK_GSCLRTND_333, "aclk_gsclrtnd_333",
> -			"mout_aclk_gscl_333_user", ENABLE_ACLK_GSCL, 5, 0, 0),
> +			"mout_aclk_gscl_333_user", ENABLE_ACLK_GSCL, 5,
> +			CLK_IGNORE_UNUSED, 0),
>  	GATE(CLK_ACLK_GSCLBEND_333, "aclk_gsclbend_333",
> -			"mout_aclk_gscl_333_user", ENABLE_ACLK_GSCL, 4, 0, 0),
> +			"mout_aclk_gscl_333_user", ENABLE_ACLK_GSCL, 4,
> +			CLK_IGNORE_UNUSED, 0),

Some of the clocks you are adding CLK_IGNORE_UNUSED flag for here are
or will be handled be the related IP drivers, thus can be gated regardless
of the changes done in this patch. I would suggest to register suspend/
resume syscore ops like exynos5420_clk_syscore_ops and enable some of
clocks you're touching in this patch explicitly in the suspend() callback
and restore the registers state from before suspend() call in resume().

I've picked up patches 01/10...09/10.
In future please also copy linux-clk@...r.kernel.org on clk related patches.

-- 
Regards,
Sylwester
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