On 10/31/2016 07:08 PM, Scott Branden wrote: > Hi Rafal, > > > On 16-10-29 04:12 AM, Rafał Miłecki wrote: >> From: Rafał Miłecki <rafal@xxxxxxxxxx> >> >> Since early BCM5301X days we got abort handler that was removed by >> commit 937b12306ea79 ("ARM: BCM5301X: remove workaround imprecise abort >> fault handler"). It assumed we need to deal only with pending aborts >> left by the bootloader. Unfortunately this isn't true for BCM5301X. >> >> When probing PCI config space (device enumeration) it is expected to >> have master aborts on the PCI bus. Most bridges don't forward (or they >> allow disabling it) these errors onto the AXI/AMBA bus but not the >> Northstar (BCM5301X) one. > Should we only add this workaround code if CONFIG_PCI is on then? I think all the supported northstar devices have a PCIe controller. We could add such a CONFIG_PCI check, but I do not see a big advantage. >> iProc PCIe controller on Northstar seems to be some older one, without >> a control register for errors forwarding. It means we need to workaround >> this at platform level. All newer platforms are not affected by this >> issue. >> >> Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx> >> --- >> arch/arm/mach-bcm/bcm_5301x.c | 28 ++++++++++++++++++++++++++++ >> 1 file changed, 28 insertions(+) >> >> diff --git a/arch/arm/mach-bcm/bcm_5301x.c >> b/arch/arm/mach-bcm/bcm_5301x.c >> index c8830a2..fe067f6 100644 >> --- a/arch/arm/mach-bcm/bcm_5301x.c >> +++ b/arch/arm/mach-bcm/bcm_5301x.c >> @@ -9,14 +9,42 @@ >> #include <asm/hardware/cache-l2x0.h> >> >> #include <asm/mach/arch.h> >> +#include <asm/siginfo.h> >> +#include <asm/signal.h> >> + >> +#define FSR_EXTERNAL (1 << 12) >> +#define FSR_READ (0 << 10) >> +#define FSR_IMPRECISE 0x0406 >> >> static const char *const bcm5301x_dt_compat[] __initconst = { >> "brcm,bcm4708", >> NULL, >> }; >> >> +static int bcm5301x_abort_handler(unsigned long addr, unsigned int fsr, >> + struct pt_regs *regs) >> +{ >> + /* >> + * We want to ignore aborts forwarded from the PCIe bus that are >> + * expected and shouldn't really be passed by the PCIe controller. >> + * The biggest disadvantage is the same FSR code may be reported >> when >> + * reading non-existing APB register and we shouldn't ignore that. >> + */ >> + if (fsr == (FSR_EXTERNAL | FSR_READ | FSR_IMPRECISE)) >> + return 0; How often does this happen? Would it be useful to add a log message here? >> + >> + return 1; >> +} >> + >> +static void __init bcm5301x_init_early(void) >> +{ >> + hook_fault_code(16 + 6, bcm5301x_abort_handler, SIGBUS, BUS_OBJERR, >> + "imprecise external abort"); >> +} >> + >> DT_MACHINE_START(BCM5301X, "BCM5301X") >> .l2c_aux_val = 0, >> .l2c_aux_mask = ~0, >> .dt_compat = bcm5301x_dt_compat, >> + .init_early = bcm5301x_init_early, >> MACHINE_END >> > > Regards, > Scott -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html