[PATCH/RFC] ARM: shmobile: r8a7779: Update early timer initialisation order

[magnus.damm@gmail.com (Magnus Damm)]

On Thu, Aug 8, 2013 at 5:59 PM, Simon Horman <horms+renesas@verge.net.au> wrote:
> a894fcc2d01a89e6fe3da0845a4d80a5312e1124 ("ARM: smp_twd: Divorce smp_twd
> from local timer API") altered twd_local_timer_common_register() so that it
> may make use of late_timer_init.
>
> This is problematic on marzen with Magnus's recent patch "ARM: shmobile:
> marzen: Switch to DT_MACHINE_START" which switches marzen around to enable
> USE_OF and thus shmobile_timer_init(), which is registered as
> late_time_init by shmobile_earlytimer_init() stops being a no-op.
>
> As a work-around I have updated r8a7779_earlytimer_init() so that
> shmobile_earlytimer_init() is called after r8a7779_register_twd().
> Or in other words, the shmobile_earlytimer_init() setting of
> late_time_init overwrites that of twd_local_timer_common_register().
>
> Cc: Stephen Boyd <sboyd@codeaurora.org>
> Cc: Magnus Damm <magnus.damm@gmail.com>
> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
>
> ---
>
> This patch was created on top of a merge of next-20130807 from the
> linux-next tree and renesas-next-20130807 from my renesas tree.
>
> I expect the problem describe above to be present in the
> next version of linux-next as it will include renesas-next-20130807.
>
> I rather suspect that this fix is just papers over the problem
> at hand rather than fixing it. But it does at least fix the problem
> to the extent where the marzen board at least boots.
>
> For reference the output of /proc/interrupts after such a boot is below.
>
>             CPU0       CPU1       CPU2       CPU3
>   29:          0       9365       9363       9359       GIC   29  twd
>   59:          0          0          0          0       GIC   59  renesas_intc_irqpin.0
>   60:          5          0          0          0       GIC   60  renesas_intc_irqpin.0
>   61:          0          0          0          0       GIC   61  renesas_intc_irqpin.0
>   62:          0          0          0          0       GIC   62  renesas_intc_irqpin.0
>   64:        278          0          0          0       GIC   64  sh_tmu.0
>   76:          1          0          0          0       GIC   76  ehci_hcd:usb1, ohci_hcd:usb3
>   77:          1          0          0          0       GIC   77  ehci_hcd:usb2, ohci_hcd:usb4
>  111:          0          0          0          0       GIC  111  i2c-rcar.0
>  112:          0          0          0          0       GIC  112  i2c-rcar.2
>  113:          0          0          0          0       GIC  113  i2c-rcar.3
>  114:          0          0          0          0       GIC  114  i2c-rcar.1
>  122:         45          0          0          0       GIC  122  sh-sci.2:mux
>  132:          0          0          0          0       GIC  132  sata_rcar
>  173:          0          0          0          0       GIC  173  gpio_rcar.0
>  174:          0          0          0          0       GIC  174  gpio_rcar.1
>  175:          0          0          0          0       GIC  175  gpio_rcar.2
>  176:          0          0          0          0       GIC  176  gpio_rcar.3
>  177:          0          0          0          0       GIC  177  gpio_rcar.4
>  178:          0          0          0          0       GIC  178  gpio_rcar.5
>  179:          0          0          0          0       GIC  179  gpio_rcar.6
> 2001:          5          0          0          0  renesas_intc_irqpin.0    1  eth0
> IPI0:          0          0          0          0  CPU wakeup interrupts
> IPI1:          0          0          0          0  Timer broadcast interrupts
> IPI2:        314        340         58         33  Rescheduling interrupts
> IPI3:         22         56         34         56  Function call interrupts
> IPI4:          0          0          0          0  Single function call interrupts
> IPI5:          0          0          0          0  CPU stop interrupts
>  Err:          0
> ---
>  arch/arm/mach-shmobile/setup-r8a7779.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/mach-shmobile/setup-r8a7779.c b/arch/arm/mach-shmobile/setup-r8a7779.c
> index ddee4aa..b0f56d6 100644
> --- a/arch/arm/mach-shmobile/setup-r8a7779.c
> +++ b/arch/arm/mach-shmobile/setup-r8a7779.c
> @@ -597,8 +597,8 @@ void __init __weak r8a7779_register_twd(void) { }
>  void __init r8a7779_earlytimer_init(void)
>  {
>         r8a7779_clock_init();
> -       shmobile_earlytimer_init();
>         r8a7779_register_twd();
> +       shmobile_earlytimer_init();
>  }
>
>  void __init r8a7779_add_early_devices(void)
> --
> 1.8.3.2
>

Hi Simon,

Thanks for tracking down this issue. I think your patch looks fine to
me. Regarding Marzen DT reference, I don't think TWD is used there yet
so I doubt that it will have the same problem as the C version of the
marzen board code. One related worry is that sh73a0 may have the same
issue - or rather - judging by the code in sh73a0_earlytimer_init() it
most certainly is affected by this too. So KZM9G should also fail as
Marzen which means we need to fix sh73a0 too.

Cheers,

/ magnus