Re: [linux-sunxi] [PATCH] cpufreq: sun50i: Fix CPU speed bin detection

[OndÅej Jirman]

Hi,

On Thu, Oct 31, 2019 at 08:12:57PM +0100, megous hlavni wrote:
> Hi,
> 
> On Thu, Oct 31, 2019 at 07:55:43PM +0100, Clément Péron wrote:
> > Hi Ondrej,
> > 
> > On Thu, 31 Oct 2019 at 19:14, Ondrej Jirman <megous@xxxxxxxxxx> wrote:
> > >
> > > I have failures to boot on Orange Pi 3, because this driver determined
> > > that my SoC is from the normal bin, but my SoC only works reliably with
> > > the OPP values for the slowest bin.
> > >
> > > Looking at BSP code, I found that efuse values have following meanings
> > > on H6:
> > >
> > > - 0b000 invalid (interpreted in vendor's BSP as normal bin)
> > > - 0b001 slowest bin
> > > - 0b011 normal bin
> > > - 0b111 fastest bin
> > 
> > Maybe have some defines will be more readable no ?
> > https://megous.com/git/linux/tree/drivers/soc/sunxi/sunxi-sid.c?h=h6-4.9-bsp#n213
> 
> Hmm, Alwwinner is really funny. Unused macros that just confuse things.
> 
> #if defined(CONFIG_ARCH_SUN50IW6)
> #define TYPE_SB (0b001)
> #define TYPE_NB (0b010)
> #define TYPE_FB (0b011)

So this table is likely used on H6, from my research I was able to find
no owners of H6 with efuse value of 0b111 and one owner with efuse value
of 0b010, and one with 0b011.

So the bins map directly to decimal numbers efuse=1 (slow bin),
efuse=2 (normal bin), efuse=3 (fast bin).

So it looks like vendor code is wrong and works accidentally, due to
fast bin being interpretted as normal bin, and normal bin being interpretted
as having a wrong efuse value, which is then interpretted alter as normal bin.

https://forum.armbian.com/topic/9368-orangepi-3-h6-allwiner-chip/page/24/#comments
https://forum.armbian.com/topic/9368-orangepi-3-h6-allwiner-chip/page/25/#comments

This will still need to be verified, by respective owners using the optimized
OPP tables for their supposed SoC bins successfully, but meanwhile I think
we should base the efuse->speed grade mapping based on values observed in the
wild. That seems most prudent at the moment.

I'll send v2 with speed grade selection matching these observations, so
please don't merge this yet.

regards,
	o.

> #else
> #define TYPE_SB (0b001)
> #define TYPE_NB (0b011)
> #define TYPE_FB (0b111)
> #endif
> 
> So for H6 they define special bin values and actually use different ones
> in code. Fun.
> 
> I've sent out some testing program to Armbian forums, so hopefully, we'll
> collect some real efuse_values from real SoCs, to see what's really being
> used in the wild. If we see value 0b010, the BSP code is probably just
> wrong.
> 
> Interestingly, TYPE_NB 0b010 would be interpreted as normal bin even with
> the current BSP code, and TYPE_FB would be misdetected as TYPE_NB.
> 
> > #define SUN50I_NVEM_INVALID_CPU_OPP (0b000)
> > #define SUN50I_NVEM_LOW_CPU_OPP (0b001)
> > #define SUN50I_NVEM_NORMAL_CPU_OPP (0b011)
> > #define SUN50I_NVEM_HIGH_CPU_OPP (0b111)
> 
> I'd rather not describe meanings just yet, until we get some real-world
> data from H6 owners.
> 
> https://forum.armbian.com/topic/9368-orangepi-3-h6-allwiner-chip/?do=findComment&comment=88439
> 
> regards,
> 	o.
> 
> > Regards,
> > Clément
> > 
> > >
> > > Let's play it safe and interpret 0 as the slowest bin, but fix detection
> > > of other bins to match vendor code.
> > >
> > > Fixes: f328584f7bff ("cpufreq: Add sun50i nvmem based CPU scaling driver")
> > > Signed-off-by: Ondrej Jirman <megous@xxxxxxxxxx>
> > > ---
> > >
> > > See https://megous.com/git/linux/tree/drivers/soc/sunxi/sunxi-sid.c?h=h6-4.9-bsp#n484
> > > and https://megous.com/git/linux/tree/drivers/cpufreq/sunxi-cpufreq.c?h=h6-4.9-bsp#n428
> > > (1 is substracted from soc_bin number here!)
> > >
> > >  drivers/cpufreq/sun50i-cpufreq-nvmem.c | 5 ++++-
> > >  1 file changed, 4 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/cpufreq/sun50i-cpufreq-nvmem.c b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > > index df35ef3ef567..41dad03e245c 100644
> > > --- a/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > > +++ b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > > @@ -71,9 +71,12 @@ static int sun50i_cpufreq_get_efuse(u32 *versions)
> > >         efuse_value = (*speedbin >> NVMEM_SHIFT) & NVMEM_MASK;
> > >         switch (efuse_value) {
> > >         case 0b0001:
> > > -               *versions = 1;
> > > +               *versions = 0;
> > >                 break;
> > >         case 0b0011:
> > > +               *versions = 1;
> > > +               break;
> > > +       case 0b0111:
> > >                 *versions = 2;
> > >                 break;
> > >         default:
> > > --
> > > 2.23.0
> > >
> > > --
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