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Commit 8e20d733 authored by Jagadeesh Kona's avatar Jagadeesh Kona
Browse files

clk: qcom: gcc-shima: Enable clocks for pm8008 by default 



The pm8008 regulator is connected over I2C and the I2C device configures
its clocks in runtime_resume and runtime_suspend. These callbacks are
triggered from the pm8008 driver's regmap calls. This means regulator
framework requests for pm8008 call into the clock framework with the
regulator framework locks held. The qcom clock providers also call into
the regulator framework with the clock framework locks held. If thread A
makes a pm8008 request at the same time thread B makes a clock request,
then it can result in deadlocks. Thread A will be stuck waiting on the
clock locks while thread B is stuck waiting on the regulator locks.

To prevent these deadlocks, enable the I2C clocks required for pm8008 by
default during probe and stop registering them with the framework. This
NOPs any client requests, since of_clk_get() returns NULL when passed an
unregistered clock and all other clock APIs return success before
grabbing any locks when passed NULL.

Change-Id: I3180f022b8ea913b4cd99b85260e72a7fa1b0693
Signed-off-by: default avatarMike Tipton <mdtipton@codeaurora.org>
Signed-off-by: default avatarJagadeesh Kona <jkona@codeaurora.org>
parent ac50d9af

drivers/clk/qcom/gcc-shima.c

+14 −51
Original line number Diff line number Diff line
@@ -2528,24 +2528,6 @@ static struct clk_branch gcc_qupv3_wrap1_s4_clk = { 
	},

};



static struct clk_branch gcc_qupv3_wrap1_s5_clk = {

	.halt_reg = 0x185fc,

	.halt_check = BRANCH_HALT_VOTED,

	.clkr = {

		.enable_reg = 0x52008,

		.enable_mask = BIT(27),

		.hw.init = &(struct clk_init_data){

			.name = "gcc_qupv3_wrap1_s5_clk",

			.parent_data = &(const struct clk_parent_data){

				.hw = &gcc_qupv3_wrap1_s5_clk_src.clkr.hw,

			},

			.num_parents = 1,

			.flags = CLK_SET_RATE_PARENT,

			.ops = &clk_branch2_ops,

		},

	},

};



static struct clk_branch gcc_qupv3_wrap1_s6_clk = {

	.halt_reg = 0x1872c,

	.halt_check = BRANCH_HALT_VOTED,
@@ -2612,36 +2594,6 @@ static struct clk_branch gcc_qupv3_wrap_0_s_ahb_clk = { 
	},

};



static struct clk_branch gcc_qupv3_wrap_1_m_ahb_clk = {

	.halt_reg = 0x18004,

	.halt_check = BRANCH_HALT_VOTED,

	.hwcg_reg = 0x18004,

	.hwcg_bit = 1,

	.clkr = {

		.enable_reg = 0x52008,

		.enable_mask = BIT(20),

		.hw.init = &(struct clk_init_data){

			.name = "gcc_qupv3_wrap_1_m_ahb_clk",

			.ops = &clk_branch2_ops,

		},

	},

};



static struct clk_branch gcc_qupv3_wrap_1_s_ahb_clk = {

	.halt_reg = 0x18008,

	.halt_check = BRANCH_HALT_VOTED,

	.hwcg_reg = 0x18008,

	.hwcg_bit = 1,

	.clkr = {

		.enable_reg = 0x52008,

		.enable_mask = BIT(21),

		.hw.init = &(struct clk_init_data){

			.name = "gcc_qupv3_wrap_1_s_ahb_clk",

			.ops = &clk_branch2_ops,

		},

	},

};



static struct clk_branch gcc_sdcc1_ahb_clk = {

	.halt_reg = 0x75004,

	.halt_check = BRANCH_HALT,
@@ -3355,7 +3307,6 @@ static struct clk_regmap *gcc_shima_clocks[] = { 
	[GCC_QUPV3_WRAP1_S3_CLK_SRC] = &gcc_qupv3_wrap1_s3_clk_src.clkr,

	[GCC_QUPV3_WRAP1_S4_CLK] = &gcc_qupv3_wrap1_s4_clk.clkr,

	[GCC_QUPV3_WRAP1_S4_CLK_SRC] = &gcc_qupv3_wrap1_s4_clk_src.clkr,

	[GCC_QUPV3_WRAP1_S5_CLK] = &gcc_qupv3_wrap1_s5_clk.clkr,

	[GCC_QUPV3_WRAP1_S5_CLK_SRC] = &gcc_qupv3_wrap1_s5_clk_src.clkr,

	[GCC_QUPV3_WRAP1_S6_CLK] = &gcc_qupv3_wrap1_s6_clk.clkr,

	[GCC_QUPV3_WRAP1_S6_CLK_SRC] = &gcc_qupv3_wrap1_s6_clk_src.clkr,
@@ -3363,8 +3314,6 @@ static struct clk_regmap *gcc_shima_clocks[] = { 
	[GCC_QUPV3_WRAP1_S7_CLK_SRC] = &gcc_qupv3_wrap1_s7_clk_src.clkr,

	[GCC_QUPV3_WRAP_0_M_AHB_CLK] = &gcc_qupv3_wrap_0_m_ahb_clk.clkr,

	[GCC_QUPV3_WRAP_0_S_AHB_CLK] = &gcc_qupv3_wrap_0_s_ahb_clk.clkr,

	[GCC_QUPV3_WRAP_1_M_AHB_CLK] = &gcc_qupv3_wrap_1_m_ahb_clk.clkr,

	[GCC_QUPV3_WRAP_1_S_AHB_CLK] = &gcc_qupv3_wrap_1_s_ahb_clk.clkr,

	[GCC_SDCC1_AHB_CLK] = &gcc_sdcc1_ahb_clk.clkr,

	[GCC_SDCC1_APPS_CLK] = &gcc_sdcc1_apps_clk.clkr,

	[GCC_SDCC1_APPS_CLK_SRC] = &gcc_sdcc1_apps_clk_src.clkr,
@@ -3520,6 +3469,20 @@ static int gcc_shima_probe(struct platform_device *pdev) 
	if (ret)

		return ret;



	/*

	 * Enable clocks required by the i2c-connected pm8008 regulators. Don't

	 * register them with the clock framework so that client requests are

	 * short-circuited before grabbing the enable/prepare locks. This

	 * prevents deadlocks between the clk/regulator frameworks.

	 *

	 *	gcc_qupv3_wrap_1_m_ahb_clk

	 *	gcc_qupv3_wrap_1_s_ahb_clk

	 *	gcc_qupv3_wrap1_s5_clk

	 */

	regmap_update_bits(regmap, 0x52008, BIT(20), BIT(20));

	regmap_update_bits(regmap, 0x52008, BIT(21), BIT(21));

	regmap_update_bits(regmap, 0x52008, BIT(27), BIT(27));



	ret = qcom_cc_really_probe(pdev, &gcc_shima_desc, regmap);

	if (ret) {

		dev_err(&pdev->dev, "Failed to register GCC clocks\n");