[PATCH 6/6] clk: samsung: exynos850: Keep some crucial clocks running

[Sam Protsenko]

Some clocks shouldn't be automatically disabled in clk_disable_unused(),
otherwise kernel hangs. Mark those clocks with:
  - CLK_IS_CRITICAL flag, when there won't be any consumers for that
    clock, but system can't function when it's gated
  - CLK_IGNORE_UNUSED flag, when consumer driver will be probably added
    later

That makes it possible to run the kernel without passing the
"clk_ignore_unused" param.

Next clocks were modified:
  - "gout_dpu_cmu_dpu_pclk":	CLK_IGNORE_UNUSED

    Will be enabled later in DSIM driver (Display Serial Interface
    Master).

  - "gout_gpio_peri_pclk":	CLK_IGNORE_UNUSED
    "gout_gpio_cmgp_pclk":	CLK_IGNORE_UNUSED
    "gout_gpio_hsi_pclk":	CLK_IGNORE_UNUSED

    Should be probably enabled in corresponding GPIO driver later, or
    made CLK_IS_CRITICAL. "gout_gpio_peri_clk" is actually used by LEDs
    on Exynos850-based dev board, so kernel hangs if this clock is not
    running. Other clocks were marked as "ignore unused" to prevent
    similar issues for other use cases or boards that might be added
    later.

  - "gout_cci_aclk":		CLK_IS_CRITICAL

    CCI (Cache Coherent Interconnect): obviously is critical.

  - "gout_gic_clk":		CLK_IS_CRITICAL

    GIC (Generic Interrupt Controller): obviously is critical.

Signed-off-by: Sam Protsenko <semen.protsenko at linaro.org>
---
 drivers/clk/samsung/clk-exynos850.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/clk/samsung/clk-exynos850.c b/drivers/clk/samsung/clk-exynos850.c
index 1d257bca8b37..c885ffb1aa24 100644
--- a/drivers/clk/samsung/clk-exynos850.c
+++ b/drivers/clk/samsung/clk-exynos850.c
@@ -596,9 +596,10 @@ static const struct samsung_gate_clock cmgp_gate_clks[] __initconst = {
 	GATE(CLK_GOUT_CMGP_ADC_S1_PCLK, "gout_adc_s1_pclk",
 	     "gout_clkcmu_cmgp_bus",
 	     CLK_CON_GAT_GOUT_CMGP_ADC_PCLK_S1, 21, 0, 0),
+	/* TODO: Should be enabled in GPIO driver (or made CLK_IS_CRITICAL) */
 	GATE(CLK_GOUT_CMGP_GPIO_PCLK, "gout_gpio_cmgp_pclk",
 	     "gout_clkcmu_cmgp_bus",
-	     CLK_CON_GAT_GOUT_CMGP_GPIO_PCLK, 21, 0, 0),
+	     CLK_CON_GAT_GOUT_CMGP_GPIO_PCLK, 21, CLK_IGNORE_UNUSED, 0),
 	GATE(CLK_GOUT_CMGP_USI0_IPCLK, "gout_cmgp_usi0_ipclk", "dout_cmgp_usi0",
 	     CLK_CON_GAT_GOUT_CMGP_USI_CMGP0_IPCLK, 21, 0, 0),
 	GATE(CLK_GOUT_CMGP_USI0_PCLK, "gout_cmgp_usi0_pclk",
@@ -685,8 +686,9 @@ static const struct samsung_gate_clock hsi_gate_clks[] __initconst = {
 	     CLK_CON_GAT_HSI_USB20DRD_TOP_I_REF_CLK_50, 21, 0, 0),
 	GATE(CLK_GOUT_USB_PHY_REF_CLK, "gout_usb_phy_ref", "oscclk",
 	     CLK_CON_GAT_HSI_USB20DRD_TOP_I_PHY_REFCLK_26, 21, 0, 0),
+	/* TODO: Should be enabled in GPIO driver (or made CLK_IS_CRITICAL) */
 	GATE(CLK_GOUT_GPIO_HSI_PCLK, "gout_gpio_hsi_pclk", "mout_hsi_bus_user",
-	     CLK_CON_GAT_GOUT_HSI_GPIO_HSI_PCLK, 21, 0, 0),
+	     CLK_CON_GAT_GOUT_HSI_GPIO_HSI_PCLK, 21, CLK_IGNORE_UNUSED, 0),
 	GATE(CLK_GOUT_MMC_CARD_ACLK, "gout_mmc_card_aclk", "mout_hsi_bus_user",
 	     CLK_CON_GAT_GOUT_HSI_MMC_CARD_I_ACLK, 21, 0, 0),
 	GATE(CLK_GOUT_MMC_CARD_SDCLKIN, "gout_mmc_card_sdclkin",
@@ -869,9 +871,10 @@ static const struct samsung_gate_clock peri_gate_clks[] __initconst = {
 	     CLK_CON_GAT_GOUT_PERI_WDT_0_PCLK, 21, 0, 0),
 	GATE(CLK_GOUT_WDT1_PCLK, "gout_wdt1_pclk", "mout_peri_bus_user",
 	     CLK_CON_GAT_GOUT_PERI_WDT_1_PCLK, 21, 0, 0),
+	/* TODO: Should be enabled in GPIO driver (or made CLK_IS_CRITICAL) */
 	GATE(CLK_GOUT_GPIO_PERI_PCLK, "gout_gpio_peri_pclk",
 	     "mout_peri_bus_user",
-	     CLK_CON_GAT_GOUT_PERI_GPIO_PERI_PCLK, 21, 0, 0),
+	     CLK_CON_GAT_GOUT_PERI_GPIO_PERI_PCLK, 21, CLK_IGNORE_UNUSED, 0),
 };
 
 static const struct samsung_cmu_info peri_cmu_info __initconst = {
@@ -954,10 +957,12 @@ static const struct samsung_div_clock core_div_clks[] __initconst = {
 };
 
 static const struct samsung_gate_clock core_gate_clks[] __initconst = {
+	/* CCI (interconnect) clock must be always running */
 	GATE(CLK_GOUT_CCI_ACLK, "gout_cci_aclk", "mout_core_cci_user",
-	     CLK_CON_GAT_GOUT_CORE_CCI_550_ACLK, 21, 0, 0),
+	     CLK_CON_GAT_GOUT_CORE_CCI_550_ACLK, 21, CLK_IS_CRITICAL, 0),
+	/* GIC (interrupt controller) clock must be always running */
 	GATE(CLK_GOUT_GIC_CLK, "gout_gic_clk", "mout_core_gic",
-	     CLK_CON_GAT_GOUT_CORE_GIC_CLK, 21, 0, 0),
+	     CLK_CON_GAT_GOUT_CORE_GIC_CLK, 21, CLK_IS_CRITICAL, 0),
 	GATE(CLK_GOUT_MMC_EMBD_ACLK, "gout_mmc_embd_aclk", "dout_core_busp",
 	     CLK_CON_GAT_GOUT_CORE_MMC_EMBD_I_ACLK, 21, 0, 0),
 	GATE(CLK_GOUT_MMC_EMBD_SDCLKIN, "gout_mmc_embd_sdclkin",
@@ -1023,8 +1028,10 @@ static const struct samsung_div_clock dpu_div_clks[] __initconst = {
 };
 
 static const struct samsung_gate_clock dpu_gate_clks[] __initconst = {
+	/* TODO: Should be enabled in DSIM driver */
 	GATE(CLK_GOUT_DPU_CMU_DPU_PCLK, "gout_dpu_cmu_dpu_pclk",
-	     "dout_dpu_busp", CLK_CON_GAT_CLK_DPU_CMU_DPU_PCLK, 21, 0, 0),
+	     "dout_dpu_busp",
+	     CLK_CON_GAT_CLK_DPU_CMU_DPU_PCLK, 21, CLK_IGNORE_UNUSED, 0),
 	GATE(CLK_GOUT_DPU_DECON0_ACLK, "gout_dpu_decon0_aclk", "mout_dpu_user",
 	     CLK_CON_GAT_GOUT_DPU_ACLK_DECON0, 21, 0, 0),
 	GATE(CLK_GOUT_DPU_DMA_ACLK, "gout_dpu_dma_aclk", "mout_dpu_user",
-- 
2.30.2