Re: [PATCH v2] MIPS: Limit check_bugs32() to affected platform

[Tiezhu Yang]

On 04/15/2020 01:32 AM, Thomas Bogendoerfer wrote:
> On Sat, Apr 11, 2020 at 10:32:02AM +0800, Tiezhu Yang wrote:
> > On 04/11/2020 12:25 AM, Florian Fainelli wrote:
> > > On 4/9/2020 8:20 PM, Tiezhu Yang wrote:
> > > > In the current code, check_bugs32() only handles MIPS32 CPU type CPU_34K,
> > > > it is better to build and call it on the affected platform.
> > > >
> > > > Move check_bugs32() to the new added 34k-bugs32.c to indicate the fact that
> > > > the code is specific to the 34k CPU, and also add CONFIG_CPU_34K_BUGS32 to
> > > > control whether or not check the bugs.
> > > >
> > > > Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
> > > This is not a whole lot of code, so moving this to a separate
> > > translation unit seems a bit heavy handed, also file renames, albeit
> > > tracked properly by git are always a challenge when doing back ports.
> > Hi Florian,
> >
> > There exists the following three ways to do it, I'm fine either way,
> > maybe the first way looks better. Let us wait for the MIPS maintainer
> > to say what he prefer.
> >
> > Hi Thomas,
> >
> > What is your opinion?
> I don't see a reason for doing that at all. The 34K workaround is only
> compiled in if CONFIG_SYS_HAS_CPU_MIPS32_R2 is defined.

Hi Thomas,

Thanks for your reply. My initial thought is to build and call check_bugs32() only for 34K CPU,
because it is useless for other CPU types.

Do you mean to use the following modification?

diff --git a/arch/mips/include/asm/bugs.h b/arch/mips/include/asm/bugs.h
index d72dc6e..743604f 100644
--- a/arch/mips/include/asm/bugs.h
+++ b/arch/mips/include/asm/bugs.h
@@ -35,7 +35,9 @@ static inline void check_bugs(void)
         unsigned int cpu = smp_processor_id();

         cpu_data[cpu].udelay_val = loops_per_jiffy;
-       check_bugs32();
+
+       if (IS_ENABLED(CONFIG_CPU_MIPS32_R2))
+               check_bugs32();

         if (IS_ENABLED(CONFIG_CPU_R4X00_BUGS64))
                 check_bugs64();
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index 6ab6b03..383500b 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -461,7 +461,8 @@ static inline void cpu_set_mt_per_tc_perf(struct
cpuinfo_mips *c)
                 c->options |= MIPS_CPU_MT_PER_TC_PERF_COUNTERS;
  }

-static inline void check_errata(void)
+#ifdef CONFIG_CPU_MIPS32_R2
+static inline void check_errata32(void)
  {
         struct cpuinfo_mips *c = &current_cpu_data;

@@ -482,8 +483,9 @@ static inline void check_errata(void)

  void __init check_bugs32(void)
  {
-       check_errata();
+       check_errata32();
  }
+#endif /* CONFIG_CPU_MIPS32_R2 */

  /*
   * Probe whether cpu has config register by trying to play with


Thanks,

Tiezhu Yang


> Thomas.