[Resending with some addresses converted to @mips.com]
On Mon, Feb 08 2016, Paul Burton wrote:
> Commit c014d164f21d ("MIPS: Add platform callback before initializing
> the L2 cache") added a platform_early_l2_init function in order to allow
> platforms to probe for the CM before L2 initialisation is performed, so
> that CM GCRs are available to mips_sc_probe.
>
> That commit actually fails to do anything useful, since it checks
> mips_cm_revision to determine whether it should call mips_cm_probe but
> the result of mips_cm_revision will always be 0 until mips_cm_probe has
> been called. Thus the "early" mips_cm_probe call never occurs.
>
> Fix this & drop the useless weak platform_early_l2_init function by
> simply calling mips_cm_probe from setup_arch. For platforms that don't
> select CONFIG_MIPS_CM this will be a no-op, and for those that do it
> removes the requirement for them to call mips_cm_probe manually
> (although doing so isn't harmful for now).
>
> Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
Hi,
this change breaks the "gnubee" open-hardware NAS board (gnubee.org),
which is based on a mediatek mt7621 SOC (which admittedly needs a bunch
of other patches to work at all).
I forward ported the patches from a mostly-working 4.4-based release to
upstream and it didn't even print anything to the console. "git
bisect" led me to this patch.
Reverting the change to setup_arch() means my mainline-based kernel
gets a lot further.
Based on the description above, I thought that maybe I should just
disabled CONFIG_MIPS_CM, but that is selected automatically by
CONFIG_MIPS_GIC, and I suspect that I need that.
Can you suggest anything I might try to isolate why mips_cm_probe()
might be causing a problem on this hardware?
Thanks,
NeilBrown
> ---
>
> arch/mips/kernel/setup.c | 1 +
> arch/mips/mm/sc-mips.c | 10 ----------
> arch/mips/mti-malta/malta-init.c | 8 --------
> 3 files changed, 1 insertion(+), 18 deletions(-)
>
> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> index 569a7d5..5fdaf8b 100644
> --- a/arch/mips/kernel/setup.c
> +++ b/arch/mips/kernel/setup.c
> @@ -782,6 +782,7 @@ static inline void prefill_possible_map(void) {}
> void __init setup_arch(char **cmdline_p)
> {
> cpu_probe();
> + mips_cm_probe();
> prom_init();
>
> setup_early_fdc_console();
> diff --git a/arch/mips/mm/sc-mips.c b/arch/mips/mm/sc-mips.c
> index 3bd0597..2496475 100644
> --- a/arch/mips/mm/sc-mips.c
> +++ b/arch/mips/mm/sc-mips.c
> @@ -181,10 +181,6 @@ static int __init mips_sc_probe_cm3(void)
> return 1;
> }
>
> -void __weak platform_early_l2_init(void)
> -{
> -}
> -
> static inline int __init mips_sc_probe(void)
> {
> struct cpuinfo_mips *c = ¤t_cpu_data;
> @@ -194,12 +190,6 @@ static inline int __init mips_sc_probe(void)
> /* Mark as not present until probe completed */
> c->scache.flags |= MIPS_CACHE_NOT_PRESENT;
>
> - /*
> - * Do we need some platform specific probing before
> - * we configure L2?
> - */
> - platform_early_l2_init();
> -
> if (mips_cm_revision() >= CM_REV_CM3)
> return mips_sc_probe_cm3();
>
> diff --git a/arch/mips/mti-malta/malta-init.c b/arch/mips/mti-malta/malta-init.c
> index 571148c..dc2c521 100644
> --- a/arch/mips/mti-malta/malta-init.c
> +++ b/arch/mips/mti-malta/malta-init.c
> @@ -293,7 +293,6 @@ mips_pci_controller:
> console_config();
> #endif
> /* Early detection of CMP support */
> - mips_cm_probe();
> mips_cpc_probe();
>
> if (!register_cps_smp_ops())
> @@ -304,10 +303,3 @@ mips_pci_controller:
> return;
> register_up_smp_ops();
> }
> -
> -void platform_early_l2_init(void)
> -{
> - /* L2 configuration lives in the CM3 */
> - if (mips_cm_revision() >= CM_REV_CM3)
> - mips_cm_probe();
> -}
> --
> 2.7.0
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