clk inits on OMAP happen quite early, even before slab is available. The dependency comes from the fact that the timer init code starts to use clocks and hwmod and we need clocks to be initialized by then. There are various problems doing clk inits this early, one is, not being able to do dynamic clk registrations and hence the dependency on clk-private.h. The other is, inability to debug early kernel crashes without enabling DEBUG_LL and earlyprintk. Doing early clk init also exposed another instance of a kernel panic due to a BUG() when CONFIG_DEBUG_SLAB is enabled. [ 0.000000] Kernel BUG at c01174f8 [verbose debug info unavailable] [ 0.000000] Internal error: Oops - BUG: 0 [#1] SMP ARM [ 0.000000] Modules linked in: [ 0.000000] CPU: 0 Not tainted (3.9.0-rc1-12179-g72d48f9 #6) [ 0.000000] PC is at __kmalloc+0x1d4/0x248 [ 0.000000] LR is at __clk_init+0x2e0/0x364 [ 0.000000] pc : [<c01174f8>] lr : [<c0441f54>] psr: 600001d3 [ 0.000000] sp : c076ff28 ip : c065cefc fp : c0441f54 [ 0.000000] r10: 0000001c r9 : 000080d0 r8 : c076ffd4 [ 0.000000] r7 : c074b578 r6 : c0794d88 r5 : 00000040 r4 : 00000000 [ 0.000000] r3 : 00000000 r2 : c07cac70 r1 : 000080d0 r0 : 0000001c [ 0.000000] Flags: nZCv IRQs off FIQs off Mode SVC_32 ISA ARM Segment kernel [ 0.000000] Control: 10c53c7d Table: 8000404a DAC: 00000017 [ 0.000000] Process swapper (pid: 0, stack limit = 0xc076e240) [ 0.000000] Stack: (0xc076ff28 to 0xc0770000) [ 0.000000] ff20: 22222222 c0794ec8 c06546e8 00000000 00000040 c0794d88 [ 0.000000] ff40: c074b578 c076ffd4 c07951c8 c076e000 00000000 c0441f54 c074b578 c076ffd4 [ 0.000000] ff60: c0793828 00000040 c0794d88 c074b578 c076ffd4 c0776900 c076e000 c07272ac [ 0.000000] ff80: 2f800000 c074c968 c07f93d0 c0719780 c076ffa0 c076ff98 00000000 00000000 [ 0.000000] ffa0: 00000000 00000000 00000000 00000001 c074cd6c c077b1ec 8000406a c0715724 [ 0.000000] ffc0: 00000000 00000000 00000000 00000000 00000000 c074c968 10c53c7d c0776974 [ 0.000000] ffe0: c074cd6c c077b1ec 8000406a 411fc092 00000000 80008074 00000000 00000000 [ 0.000000] [<c01174f8>] (__kmalloc+0x1d4/0x248) from [<c0441f54>] (__clk_init+0x2e0/0x364) [ 0.000000] [<c0441f54>] (__clk_init+0x2e0/0x364) from [<c07272ac>] (omap4xxx_clk_init+0xbc/0x140) [ 0.000000] [<c07272ac>] (omap4xxx_clk_init+0xbc/0x140) from [<c0719780>] (setup_arch+0x15c/0x284) [ 0.000000] [<c0719780>] (setup_arch+0x15c/0x284) from [<c0715724>] (start_kernel+0x7c/0x334) [ 0.000000] [<c0715724>] (start_kernel+0x7c/0x334) from [<80008074>] (0x80008074) [ 0.000000] Code: e5883004 e1a00006 e28dd00c e8bd8ff0 (e7f001f2) [ 0.000000] ---[ end trace 1b75b31a2719ed1c ]--- [ 0.000000] Kernel panic - not syncing: Attempted to kill the idle task! It was a know issue, that slab allocations would fail when common clock core tries to cache parent pointers for mux clocks on OMAP, and hence a patch 'clk: Allow late cache allocation for clk->parents, commit 7975059d' was added to work this problem around. A BUG() within kmalloc() with CONFIG_DEBUG_SLAB enabled was completely overlooked causing this regression. More details on the issue reported can be found here, http://www.mail-archive.com/linux-omap@xxxxxxxxxxxxxxx/msg85932.html With all these issues around clk inits happening way too early, it makes sense to atleast move them to a point where dynamic memory allocations are possible. So move them to a point just before the timer code starts using clocks and hwmod. This should atleast pave way for clk inits on OMAP moving to dynamic clock registrations instead of using the static macros defined in clk-private.h. The issue with kernel panic while CONFIG_DEBUG_SLAB is enabled was reported by Piotr Haber and Tony Lindgren and this patch fixes the reported issue as well. Reported-by: Piotr Haber <phaber@xxxxxxxxxxxx> Reported-by: Tony Lindgren <tony@xxxxxxxxxxx> Signed-off-by: Rajendra Nayak <rnayak@xxxxxx> --- applies on 3.9-rc3 and tested on omap4 pandaES, omap3 beagle XM, and am335x bone. v2: updated changelog based on comments from Tony Lindgren arch/arm/mach-omap2/common.h | 3 +++ arch/arm/mach-omap2/io.c | 18 ++++++++++++------ arch/arm/mach-omap2/timer.c | 4 ++++ 3 files changed, 19 insertions(+), 6 deletions(-) diff --git a/arch/arm/mach-omap2/common.h b/arch/arm/mach-omap2/common.h index 40f4a03..d6ba13e 100644 --- a/arch/arm/mach-omap2/common.h +++ b/arch/arm/mach-omap2/common.h @@ -293,5 +293,8 @@ extern void omap_reserve(void); struct omap_hwmod; extern int omap_dss_reset(struct omap_hwmod *); +/* SoC specific clock initializer */ +extern int (*omap_clk_init)(void); + #endif /* __ASSEMBLER__ */ #endif /* __ARCH_ARM_MACH_OMAP2PLUS_COMMON_H */ diff --git a/arch/arm/mach-omap2/io.c b/arch/arm/mach-omap2/io.c index 2c3fdd6..5c445ca 100644 --- a/arch/arm/mach-omap2/io.c +++ b/arch/arm/mach-omap2/io.c @@ -55,6 +55,12 @@ #include "prm44xx.h" /* + * omap_clk_init: points to a function that does the SoC-specific + * clock initializations + */ +int (*omap_clk_init)(void); + +/* * The machine specific code may provide the extra mapping besides the * default mapping provided here. */ @@ -397,7 +403,7 @@ void __init omap2420_init_early(void) omap242x_clockdomains_init(); omap2420_hwmod_init(); omap_hwmod_init_postsetup(); - omap2420_clk_init(); + omap_clk_init = omap2420_clk_init; } void __init omap2420_init_late(void) @@ -427,7 +433,7 @@ void __init omap2430_init_early(void) omap243x_clockdomains_init(); omap2430_hwmod_init(); omap_hwmod_init_postsetup(); - omap2430_clk_init(); + omap_clk_init = omap2430_clk_init; } void __init omap2430_init_late(void) @@ -462,7 +468,7 @@ void __init omap3_init_early(void) omap3xxx_clockdomains_init(); omap3xxx_hwmod_init(); omap_hwmod_init_postsetup(); - omap3xxx_clk_init(); + omap_clk_init = omap3xxx_clk_init; } void __init omap3430_init_early(void) @@ -500,7 +506,7 @@ void __init ti81xx_init_early(void) omap3xxx_clockdomains_init(); omap3xxx_hwmod_init(); omap_hwmod_init_postsetup(); - omap3xxx_clk_init(); + omap_clk_init = omap3xxx_clk_init; } void __init omap3_init_late(void) @@ -568,7 +574,7 @@ void __init am33xx_init_early(void) am33xx_clockdomains_init(); am33xx_hwmod_init(); omap_hwmod_init_postsetup(); - am33xx_clk_init(); + omap_clk_init = am33xx_clk_init; } #endif @@ -593,7 +599,7 @@ void __init omap4430_init_early(void) omap44xx_clockdomains_init(); omap44xx_hwmod_init(); omap_hwmod_init_postsetup(); - omap4xxx_clk_init(); + omap_clk_init = omap4xxx_clk_init; } void __init omap4430_init_late(void) diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c index 2bdd4cf..f62b509 100644 --- a/arch/arm/mach-omap2/timer.c +++ b/arch/arm/mach-omap2/timer.c @@ -547,6 +547,8 @@ static inline void __init realtime_counter_init(void) clksrc_nr, clksrc_src) \ void __init omap##name##_gptimer_timer_init(void) \ { \ + if (omap_clk_init) \ + omap_clk_init(); \ omap_dmtimer_init(); \ omap2_gp_clockevent_init((clkev_nr), clkev_src, clkev_prop); \ omap2_gptimer_clocksource_init((clksrc_nr), clksrc_src); \ @@ -556,6 +558,8 @@ void __init omap##name##_gptimer_timer_init(void) \ clksrc_nr, clksrc_src) \ void __init omap##name##_sync32k_timer_init(void) \ { \ + if (omap_clk_init) \ + omap_clk_init(); \ omap_dmtimer_init(); \ omap2_gp_clockevent_init((clkev_nr), clkev_src, clkev_prop); \ /* Enable the use of clocksource="gp_timer" kernel parameter */ \ -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
