Hi Robin,

On Tue, 18 Mar 2025 at 18:24, Robin Murphy [off-list ref] wrote:

On 18/03/2025 4:37 pm, Geert Uytterhoeven wrote:
[...]

quoted

Thanks for your patch, which is now commit bcb81ac6ae3c2ef9 ("iommu:
Get DT/ACPI parsing into the proper probe path") in iommu/next.

This patch triggers two issues on R-Car Gen3 platforms:

1. I am seeing a warning on Renesas Salvator-XS with R-Car M3N
(but not on the similar board with R-Car H3), and only for SATA[1].
Unfortunately commit 73d2f10957f517e5 ("iommu: Don't warn prematurely
about dodgy probes") does not help:

[...]

quoted

     Call trace:
      __iommu_probe_device+0x208/0x38c (P)
      iommu_probe_device+0x34/0x74
      of_iommu_configure+0x128/0x200
      of_dma_configure_id+0xdc/0x1d4
      platform_dma_configure+0x48/0x6c
      really_probe+0xf0/0x260
      __driver_probe_device+0xec/0x104
      driver_probe_device+0x3c/0xc0

Hurrah, this is the warning doing the correct job - something *is* off
if we're now getting here without the IOMMU configuration being done
already (for a normal device with no other funny business going on).

quoted

2. The IOMMU driver's iommu_ops.of_xlate() callback is called about
three times as much as before:

That would suggest that the fwspec gets set up OK, then something later
in the __iommu_probe_device() path fails and tears it down again, so the
next attempt starts from scratch. Do you see the "Cannot attach to
IPMMU" message firing?

I do not see such messages.

And similarly to the Rockchip case, does the
below help?

The below is basically the same as your "[PATCH] iommu/ipmmu-vmsa:
Register in a sensible order"[1].  While that fixes my first issue,
it does not fix the second (harmless?) issue.

Note that I only noticed the second issue because I have local debug
code in soc_device_match().  Perhaps it happens, unnoticed, on other
systems too?

Thanks!

[1] https://lore.kernel.org/53be6667544de65a15415b699e38a9a965692e45.1742481687.git.robin.murphy@arm.com/ (local)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds