From d48866fefdac239a4e02777e712aad60db9ee8a8 Mon Sep 17 00:00:00 2001 From: Shawn Guo Date: Wed, 16 Oct 2013 19:52:00 +0800 Subject: [PATCH] ARM: imx: ensure dsm_request signal is not asserted when setting LPM There is a defect in imx6 LPM design. When SW tries to enter low power mode with following sequence, the chip will enter low power mode before A9 CPU execute WFI instruction: 1. Set CCM_CLPCR[1:0] to 2'b00; 2. ARM CPU enters WFI; 3. ARM CPU wakeup from an interrupt event, which is masked by GPC or not visible to GPC, such as interrupt from local timer; 4. Set CCM_CLPCR[1:0] to 2'b01 or 2'b10; 5. ARM CPU execute WFI. Before the last step, the chip will enter WAIT mode if CCM_CLPCR[1:0] is set to 2'b01, or enter STOP mode if CCM_CLPCR[1:0] is set to 2'b10. The patch implements a recommended workaround for this issue. 1. SW triggers irq #32(IOMUX) to be always pending manually by setting IOMUX_GPR1_GINT bit; 2. SW should then unmask it in GPC before setting CCM LPM; 3. SW should mask it right after CCM LPM is set (bit0-1 of CCM_CLPCR). Signed-off-by: Shawn Guo --- arch/arm/mach-imx/common.h | 3 +++ arch/arm/mach-imx/gpc.c | 4 ++-- arch/arm/mach-imx/pm-imx6q.c | 26 ++++++++++++++++++++++++++ 3 files changed, 31 insertions(+), 2 deletions(-) diff --git a/arch/arm/mach-imx/common.h b/arch/arm/mach-imx/common.h index fde6661ef70d..7cbe22d0c6e9 100644 --- a/arch/arm/mach-imx/common.h +++ b/arch/arm/mach-imx/common.h @@ -13,6 +13,7 @@ #include +struct irq_data; struct platform_device; struct pt_regs; struct clk; @@ -136,6 +137,8 @@ void imx_gpc_pre_suspend(void); void imx_gpc_post_resume(void); void imx_gpc_mask_all(void); void imx_gpc_restore_all(void); +void imx_gpc_irq_mask(struct irq_data *d); +void imx_gpc_irq_unmask(struct irq_data *d); void imx_anatop_init(void); void imx_anatop_pre_suspend(void); void imx_anatop_post_resume(void); diff --git a/arch/arm/mach-imx/gpc.c b/arch/arm/mach-imx/gpc.c index 44a65e9ff1fc..586e0171a652 100644 --- a/arch/arm/mach-imx/gpc.c +++ b/arch/arm/mach-imx/gpc.c @@ -90,7 +90,7 @@ void imx_gpc_restore_all(void) writel_relaxed(gpc_saved_imrs[i], reg_imr1 + i * 4); } -static void imx_gpc_irq_unmask(struct irq_data *d) +void imx_gpc_irq_unmask(struct irq_data *d) { void __iomem *reg; u32 val; @@ -105,7 +105,7 @@ static void imx_gpc_irq_unmask(struct irq_data *d) writel_relaxed(val, reg); } -static void imx_gpc_irq_mask(struct irq_data *d) +void imx_gpc_irq_mask(struct irq_data *d) { void __iomem *reg; u32 val; diff --git a/arch/arm/mach-imx/pm-imx6q.c b/arch/arm/mach-imx/pm-imx6q.c index fb7d90d36672..f303b56f087c 100644 --- a/arch/arm/mach-imx/pm-imx6q.c +++ b/arch/arm/mach-imx/pm-imx6q.c @@ -13,8 +13,12 @@ #include #include #include +#include +#include +#include #include #include +#include #include #include #include @@ -116,6 +120,7 @@ static void imx6q_enable_wb(bool enable) int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode) { + struct irq_desc *iomuxc_irq_desc; u32 val = readl_relaxed(ccm_base + CLPCR); val &= ~BM_CLPCR_LPM; @@ -144,7 +149,16 @@ int imx6q_set_lpm(enum mxc_cpu_pwr_mode mode) return -EINVAL; } + /* + * Unmask the always pending IOMUXC interrupt #32 as wakeup source to + * deassert dsm_request signal, so that we can ensure dsm_request + * is not asserted when we're going to write CLPCR register to set LPM. + * After setting up LPM bits, we need to mask this wakeup source. + */ + iomuxc_irq_desc = irq_to_desc(32); + imx_gpc_irq_unmask(&iomuxc_irq_desc->irq_data); writel_relaxed(val, ccm_base + CLPCR); + imx_gpc_irq_mask(&iomuxc_irq_desc->irq_data); return 0; } @@ -193,8 +207,20 @@ void __init imx6q_pm_set_ccm_base(void __iomem *base) void __init imx6q_pm_init(void) { + struct regmap *gpr; + WARN_ON(!ccm_base); + /* + * Force IOMUXC irq pending, so that the interrupt to GPC can be + * used to deassert dsm_request signal when the signal gets + * asserted unexpectedly. + */ + gpr = syscon_regmap_lookup_by_compatible("fsl,imx6q-iomuxc-gpr"); + if (!IS_ERR(gpr)) + regmap_update_bits(gpr, IOMUXC_GPR1, IMX6Q_GPR1_GINT, + IMX6Q_GPR1_GINT); + /* Set initial power mode */ imx6q_set_lpm(WAIT_CLOCKED);