Re: [PATCH] soc/tegra: fuse: Fix spurious straps warning on SMCCC platforms

[Jon Hunter <jonathanh@nvidia.com>]

On 22/06/2026 08:24, Thierry Reding wrote:
> On Mon, Jun 15, 2026 at 08:32:25AM -0700, Breno Leitao wrote:
>>
>> On Thu, Jun 04, 2026 at 03:36:17AM -0700, Breno Leitao wrote:
>>> My Grace host started to show this warning:
>>>    WARNING: drivers/soc/tegra/fuse/tegra-apbmisc.c:120 at tegra_read_straps
>>>     tegra30_fuse_add_randomness
>>>     tegra30_fuse_init
>>>     tegra_fuse_probe
>>>
>>> tegra_read_straps() warns when the static "chipid" cache is still zero,
>>> using it as a proxy for "APBMISC has been initialised". However chipid
>>> is only ever populated lazily by tegra_read_chipid() when it reads the
>>> APBMISC register.
>>>
>>> Guard on apbmisc_base instead, which is set unconditionally in
>>> tegra_init_apbmisc_resources() for all platforms and is already the
>>> sentinel used by tegra_read_chipid().
>>>
>>> Fixes: c71f213fa5af ("soc/tegra: fuse: Warn if straps are not ready")
>>> Signed-off-by: Breno Leitao <leitao@debian.org>
>>> ---
>>>   drivers/soc/tegra/fuse/tegra-apbmisc.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/soc/tegra/fuse/tegra-apbmisc.c b/drivers/soc/tegra/fuse/tegra-apbmisc.c
>>> index 87ae63a7e52d..7aba7c58bad0 100644
>>> --- a/drivers/soc/tegra/fuse/tegra-apbmisc.c
>>> +++ b/drivers/soc/tegra/fuse/tegra-apbmisc.c
>>> @@ -117,7 +117,7 @@ bool tegra_is_silicon(void)
>>>   
>>>   u32 tegra_read_straps(void)
>>>   {
>>> -	WARN(!chipid, "Tegra ABP MISC not yet available\n");
>>> +	WARN(!apbmisc_base, "Tegra ABP MISC not yet available\n");
>>
>> Hello Thierry,
>>
>> Have you had a chance to look at this one? This is showing up in my
>> Grace all the time.
> 
> Yeah, sorry for the delay. You're right in that we now get the warning
> until we end up calling tegra_read_chipid(). However, I don't think the
> Fixes: reference is right. I think this started showing up after:
> 
>    8b8ee2e56f95 ("soc/tegra: Use ARM SMCCC to get chip ID, revision, and platform info")
> 
> I don't think we accounted for tegra_read_straps() in that case and I
> suspect that we're not seeing this elsewhere because we do end up
> calling tegra_read_chipid() earlier in DT systems whereas for ACPI it
> might only get called at a later point, if at all.
> 
> There's also this patch:
> 
>    https://lore.kernel.org/linux-tegra/20260514051252.2401568-1-kkartik@nvidia.com/
> 
> IIUC, that's the only place where tegra_read_straps() gets called on
> ACPI systems. Would you mind testing that patch (without the one that
> we're currently discussing) to confirm that that's the only callsite?
> It doesn't really matter either way, because applying your fix here is
> the right thing to do, but it'd still be useful as a data point.
> 
> If you don't have any objections, I'm going to replace the Fixes: line,
> but otherwise this patch looks good.
> 
> Also, I'm going to check if we can get some better coverage in our daily
> testing for the ACPI platforms. Do you happen to run any daily tests on
> your systems for linux-next?

FWIW I also see this on Tegra194 and Tegra234 (I have not checked others) ...

  WARNING KERN ------------[ cut here ]------------
  WARNING KERN Tegra ABP MISC not yet available
  WARNING KERN WARNING: drivers/soc/tegra/fuse/tegra-apbmisc.c:120 at tegra_read_straps+0x40/0x58, CPU#0: swapper/0/1
  WARNING KERN Modules linked in:
  WARNING KERN CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 7.1.0-g8cd8cf7a07e5 #1 PREEMPT
  WARNING KERN Hardware name: NVIDIA Jetson AGX Orin Developer Kit (DT)
  WARNING KERN pstate: 60000009 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  WARNING KERN pc : tegra_read_straps+0x40/0x58
  WARNING KERN lr : tegra_read_straps+0x40/0x58
  WARNING KERN sp : ffff80008327bcb0
  WARNING KERN x29: ffff80008327bcb0 x28: 0000000000000000 x27: 0000000000000000
  WARNING KERN x26: 0000000000000000 x25: ffff800083146000 x24: 0000000000000000
  WARNING KERN x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000000
  WARNING KERN x20: ffff8000831ae000 x19: ffff8000831ae850 x18: fffffffffffe1fe8
  WARNING KERN x17: ffff800083042c38 x16: ffff800083042ca8 x15: ffff800082c444d8
  WARNING KERN x14: 0000000000000030 x13: 0a656c62616c6961 x12: 7661207465792074
  WARNING KERN x11: ffff800082c44558 x10: 0000000000000018 x9 : ffff800082c44558
  WARNING KERN x8 : 000000000000006b x7 : ffff800082c9c558 x6 : ffff800082c9c558
  WARNING KERN x5 : 0000000000017fe8 x4 : 0000000000000000 x3 : 0000000000000000
  WARNING KERN x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0000801c3000
  WARNING KERN Call trace:
  WARNING KERN  tegra_read_straps+0x40/0x58 (P)
  WARNING KERN  tegra30_fuse_init+0x70/0x13c
  WARNING KERN  tegra_init_fuse+0x154/0x1ec
  WARNING KERN  do_one_initcall+0x7c/0x1c0
  WARNING KERN  kernel_init_freeable+0x108/0x2ec
  WARNING KERN  kernel_init+0x24/0x1e0
  WARNING KERN  ret_from_fork+0x10/0x20
  WARNING KERN ---[ end trace 0000000000000000 ]---

Jon

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