From 1a3388d506bf5b45bb283e6a4c4706cfb4897333 Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Thu, 3 Oct 2019 14:50:31 -0600 Subject: [PATCH 1/3] ARM: tegra: Enable PLLP bypass during Tegra124 LP1 For a little over a year, U-Boot has configured the flow controller to perform automatic RAM re-repair on off->on power transitions of the CPU rail[1]. This is mandatory for correct operation of Tegra124. However, RAM re-repair relies on certain clocks, which the kernel must enable and leave running. PLLP is one of those clocks. This clock is shut down during LP1 in order to save power. Enable bypass (which I believe routes osc_div_clk, essentially the crystal clock, to the PLL output) so that this clock signal toggles even though the PLL is not active. This is required so that LP1 power mode (system suspend) operates correctly. The bypass configuration must then be undone when resuming from LP1, so that all peripheral clocks run at the expected rate. Without this, many peripherals won't work correctly; for example, the UART baud rate would be incorrect. NVIDIA's downstream kernel code only does this if not compiled for Tegra30, so the added code is made conditional upon the chip ID. NVIDIA's downstream code makes this change conditional upon the active CPU cluster. The upstream kernel currently doesn't support cluster switching, so this patch doesn't test the active CPU cluster ID. [1] 3cc7942a4ae5 ARM: tegra: implement RAM repair Reported-by: Jonathan Hunter Cc: stable@vger.kernel.org Signed-off-by: Stephen Warren Signed-off-by: Thierry Reding --- arch/arm/mach-tegra/sleep-tegra30.S | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/arm/mach-tegra/sleep-tegra30.S b/arch/arm/mach-tegra/sleep-tegra30.S index 3341a12bbb9c..c796a97194ac 100644 --- a/arch/arm/mach-tegra/sleep-tegra30.S +++ b/arch/arm/mach-tegra/sleep-tegra30.S @@ -370,6 +370,14 @@ _pll_m_c_x_done: pll_locked r1, r0, CLK_RESET_PLLC_BASE pll_locked r1, r0, CLK_RESET_PLLX_BASE + tegra_get_soc_id TEGRA_APB_MISC_BASE, r1 + cmp r1, #TEGRA30 + beq 1f + ldr r1, [r0, #CLK_RESET_PLLP_BASE] + bic r1, r1, #(1<<31) @ disable PllP bypass + str r1, [r0, #CLK_RESET_PLLP_BASE] +1: + mov32 r7, TEGRA_TMRUS_BASE ldr r1, [r7] add r1, r1, #LOCK_DELAY @@ -630,7 +638,10 @@ tegra30_switch_cpu_to_clk32k: str r0, [r4, #PMC_PLLP_WB0_OVERRIDE] /* disable PLLP, PLLA, PLLC and PLLX */ + tegra_get_soc_id TEGRA_APB_MISC_BASE, r1 + cmp r1, #TEGRA30 ldr r0, [r5, #CLK_RESET_PLLP_BASE] + orrne r0, r0, #(1 << 31) @ enable PllP bypass on fast cluster bic r0, r0, #(1 << 30) str r0, [r5, #CLK_RESET_PLLP_BASE] ldr r0, [r5, #CLK_RESET_PLLA_BASE] From cf94a7a06a7d7d4402d7313cf622ca2823bad43c Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Thu, 3 Oct 2019 14:50:32 -0600 Subject: [PATCH 2/3] ARM: tegra: Modify reshift divider during LP1 The reshift hardware module implements the RAM re-repair process. This module uses PLLP as an input clock during LP1 resume. The input divider for this clock is typically set for PLLP's normal rate. During LP1 resume, PLLP is bypassed and so runs at the crystal rate, which is much slower. Consequently, decrease the divider so that the reshift module runs at a reasonable rate during LP1 resume. NVIDIA's downstream kernel code only does this if not compiled for Tegra30, so the added code is made conditional upon the chip ID. Signed-off-by: Stephen Warren Signed-off-by: Thierry Reding --- arch/arm/mach-tegra/sleep-tegra30.S | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/arm/mach-tegra/sleep-tegra30.S b/arch/arm/mach-tegra/sleep-tegra30.S index c796a97194ac..f01ea3be1405 100644 --- a/arch/arm/mach-tegra/sleep-tegra30.S +++ b/arch/arm/mach-tegra/sleep-tegra30.S @@ -59,6 +59,9 @@ #define CLK_RESET_PLLX_MISC3_IDDQ 3 #define CLK_RESET_PLLM_MISC_IDDQ 5 #define CLK_RESET_PLLC_MISC_IDDQ 26 +#define CLK_RESET_PLLP_RESHIFT 0x528 +#define CLK_RESET_PLLP_RESHIFT_DEFAULT 0x3b +#define CLK_RESET_PLLP_RESHIFT_ENABLE 0x3 #define CLK_RESET_CLK_SOURCE_MSELECT 0x3b4 @@ -373,9 +376,13 @@ _pll_m_c_x_done: tegra_get_soc_id TEGRA_APB_MISC_BASE, r1 cmp r1, #TEGRA30 beq 1f + ldr r1, [r0, #CLK_RESET_PLLP_BASE] bic r1, r1, #(1<<31) @ disable PllP bypass str r1, [r0, #CLK_RESET_PLLP_BASE] + + mov r1, #CLK_RESET_PLLP_RESHIFT_DEFAULT + str r1, [r0, #CLK_RESET_PLLP_RESHIFT] 1: mov32 r7, TEGRA_TMRUS_BASE @@ -644,6 +651,10 @@ tegra30_switch_cpu_to_clk32k: orrne r0, r0, #(1 << 31) @ enable PllP bypass on fast cluster bic r0, r0, #(1 << 30) str r0, [r5, #CLK_RESET_PLLP_BASE] + beq 1f + mov r0, #CLK_RESET_PLLP_RESHIFT_ENABLE + str r0, [r5, #CLK_RESET_PLLP_RESHIFT] +1: ldr r0, [r5, #CLK_RESET_PLLA_BASE] bic r0, r0, #(1 << 30) str r0, [r5, #CLK_RESET_PLLA_BASE] From 9c65b8463f41f3a9edef97e3109752159d4c6a4b Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Thu, 3 Oct 2019 14:50:33 -0600 Subject: [PATCH 3/3] ARM: tegra: Use clk_m CPU on Tegra124 LP1 resume Configure the clock controller to set an alternate clock for the CPU when it receives an IRQ during LP1 (system suspend). Specifically, use clk_m (the crystal) rather than clk_s (a 32KHz clock). Such an IRQ will be the LP1 wake event. This reduces the amount of time taken to resume from LP1. NVIDIA's downstream kernel executes this code on both Tegra30 and Tegra124, so it appears OK to make this change unconditionally. Signed-off-by: Stephen Warren Signed-off-by: Thierry Reding --- arch/arm/mach-tegra/sleep-tegra30.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/arm/mach-tegra/sleep-tegra30.S b/arch/arm/mach-tegra/sleep-tegra30.S index f01ea3be1405..02cc6ff96f30 100644 --- a/arch/arm/mach-tegra/sleep-tegra30.S +++ b/arch/arm/mach-tegra/sleep-tegra30.S @@ -670,8 +670,12 @@ tegra30_switch_cpu_to_clk32k: pll_iddq_entry r1, r5, CLK_RESET_PLLX_MISC3, CLK_RESET_PLLX_MISC3_IDDQ _no_pll_in_iddq: - /* switch to CLKS */ - mov r0, #0 /* brust policy = 32KHz */ + /* + * Switch to clk_s (32KHz); bits 28:31=0 + * Enable burst on CPU IRQ; bit 24=1 + * Set IRQ burst clock source to clk_m; bits 10:8=0 + */ + mov r0, #(1 << 24) str r0, [r5, #CLK_RESET_SCLK_BURST] ret lr