From: Michal Wilczynski Date: Mon, 23 Jun 2025 18:08:53 +0000 (+0200) Subject: clk: thead: Mark essential bus clocks as CLK_IGNORE_UNUSED X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0370395d45ca6dd53bb931978f0e91ac8dd6f1c5;p=thirdparty%2Flinux.git clk: thead: Mark essential bus clocks as CLK_IGNORE_UNUSED Probing peripherals in the AON and PERI domains, such as the PVT thermal sensor and the PWM controller, can lead to boot hangs or unresponsive devices on the LPi4A board. The root cause is that their parent bus clocks ('CLK_CPU2AON_X2H' and the 'CLK_PERISYS_APB' clocks) are automatically gated by the kernel's power-saving mechanisms when the bus is perceived as idle. Alternative solutions were investigated, including modeling the parent bus in the Device Tree with 'simple-pm-bus' or refactoring the clock driver's parentage. The 'simple-pm-bus' approach is not viable due to the lack of defined bus address ranges in the hardware manual and its creation of improper dependencies on the 'pm_runtime' API for consumer drivers. Therefore, applying the'`CLK_IGNORE_UNUSED' flag directly to the essential bus clocks is the most direct and targeted fix. This prevents the kernel from auto-gating these buses and ensures peripherals remain accessible. This change fixes the boot hang associated with the PVT sensor and resolves the functional issues with the PWM controller. Link: https://lore.kernel.org/all/9e8a12db-236d-474c-b110-b3be96edf057@samsung.com/ [1] Reviewed-by: Drew Fustini Acked-by: Stephen Boyd Signed-off-by: Michal Wilczynski Signed-off-by: Drew Fustini --- diff --git a/drivers/clk/thead/clk-th1520-ap.c b/drivers/clk/thead/clk-th1520-ap.c index ebfb1d59401d0..cf7f6bd428a0f 100644 --- a/drivers/clk/thead/clk-th1520-ap.c +++ b/drivers/clk/thead/clk-th1520-ap.c @@ -792,11 +792,12 @@ static CCU_GATE(CLK_AON2CPU_A2X, aon2cpu_a2x_clk, "aon2cpu-a2x", axi4_cpusys2_ac 0x134, BIT(8), 0); static CCU_GATE(CLK_X2X_CPUSYS, x2x_cpusys_clk, "x2x-cpusys", axi4_cpusys2_aclk_pd, 0x134, BIT(7), 0); -static CCU_GATE(CLK_CPU2AON_X2H, cpu2aon_x2h_clk, "cpu2aon-x2h", axi_aclk_pd, 0x138, BIT(8), 0); +static CCU_GATE(CLK_CPU2AON_X2H, cpu2aon_x2h_clk, "cpu2aon-x2h", axi_aclk_pd, + 0x138, BIT(8), CLK_IGNORE_UNUSED); static CCU_GATE(CLK_CPU2PERI_X2H, cpu2peri_x2h_clk, "cpu2peri-x2h", axi4_cpusys2_aclk_pd, 0x140, BIT(9), CLK_IGNORE_UNUSED); static CCU_GATE(CLK_PERISYS_APB1_HCLK, perisys_apb1_hclk, "perisys-apb1-hclk", perisys_ahb_hclk_pd, - 0x150, BIT(9), 0); + 0x150, BIT(9), CLK_IGNORE_UNUSED); static CCU_GATE(CLK_PERISYS_APB2_HCLK, perisys_apb2_hclk, "perisys-apb2-hclk", perisys_ahb_hclk_pd, 0x150, BIT(10), CLK_IGNORE_UNUSED); static CCU_GATE(CLK_PERISYS_APB3_HCLK, perisys_apb3_hclk, "perisys-apb3-hclk", perisys_ahb_hclk_pd,