Re: [PATCH v2 2/2] of: property: Add fw_devlink support for interrupts

[Saravana Kannan]

On Sat, Feb 13, 2021 at 10:54 AM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> Hi,
>
> On Thu, Jan 21, 2021 at 02:57:12PM -0800, Saravana Kannan wrote:
> > This allows fw_devlink to create device links between consumers of an
> > interrupt and the supplier of the interrupt.
> >
> > Cc: Marc Zyngier <maz@xxxxxxxxxx>
> > Cc: Kevin Hilman <khilman@xxxxxxxxxxxx>
> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> > Reviewed-by: Thierry Reding <treding@xxxxxxxxxx>
> > Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> > Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
>
> This patch causes all ppc64:powernv qemu emulations to fail.
> The problem is always the same: The root file system can not be mounted.
>
> Example:
>
> [   14.245672][    T1] VFS: Cannot open root device "sda" or unknown-block(0,0): error -6
> [   14.246063][    T1] Please append a correct "root=" boot option; here are the available partitions:
> [   14.246609][    T1] 1f00          131072 mtdblock0
> [   14.246648][    T1]  (driver?)
> [   14.247137][    T1] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
> [   14.247631][    T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.11.0-rc7-next-20210212 #1
> [   14.248166][    T1] Call Trace:
> [   14.248344][    T1] [c000000002c07a70] [c0000000008f052c] dump_stack+0x100/0x174 (unreliable)
> [   14.248780][    T1] [c000000002c07ab0] [c00000000010d0e0] panic+0x190/0x450
> [   14.249097][    T1] [c000000002c07b50] [c0000000014d1af8] mount_block_root+0x320/0x430
> [   14.249442][    T1] [c000000002c07c50] [c0000000014d1e64] prepare_namespace+0x1b0/0x204
> [   14.249798][    T1] [c000000002c07cc0] [c0000000014d1544] kernel_init_freeable+0x3dc/0x438
> [   14.250145][    T1] [c000000002c07da0] [c000000000012b7c] kernel_init+0x2c/0x170
> [   14.250466][    T1] [c000000002c07e10] [c00000000000d56c] ret_from_kernel_thread+0x5c/0x70
> [   28.068945385,5] OPAL: Reboot request...
>
> Another:
>
> [   14.273398][    T1] md: Autodetecting RAID arrays.
> [   14.273665][    T1] md: autorun ...
> [   14.273860][    T1] md: ... autorun DONE.
> [   14.275078][    T1] Waiting for root device /dev/mmcblk0...
>
> [ waits until terminated ]
>
> Key difference seems to be that PCI devices are no longer instantiated
> with this patch applied. Specifically, I see
>
> [    1.153780][    T1] pci 0005:01     : [PE# fd] Setting up window#0 0..7fffffff pg=10000^M
> [    1.154475][    T1] pci 0005:01     : [PE# fd] Enabling 64-bit DMA bypass^M
> [    1.155749][    T1] pci 0005:01:00.0: Adding to iommu group 0^M
> [    1.160543][    T1] pci 0005:00:00.0: enabling device (0105 -> 0107)^M
>
> in both cases, but (exmple nvme) I don't see
>
> [   13.520561][   T11] nvme nvme0: pci function 0005:01:00.0^M
> [   13.521747][   T45] nvme 0005:01:00.0: enabling device (0100 -> 0102)^M
>
> after this patch has been applied.
>
> Reverting th patch plus its fix resolves the problem.
>
> Bisect log attached.

Hi Guenter,

Thanks for the report.

Can you please give me the following details:
* The DTS file for the board (not the SoC).
* A boot log with the logs enabled in device_links_check_suppliers()
and device_link_add()

That should help me debug this.

Rob,

Looks like Guenter has this patch[1] too. What PPC specific IRQ hack
am I missing? Any ideas?

[1] - https://lore.kernel.org/lkml/20210209010439.3529036-1-saravanak@xxxxxxxxxx/

Thanks,
Saravana