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

[Guenter Roeck <linux@roeck-us.net>]

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@kernel.org>
> Cc: Kevin Hilman <khilman@baylibre.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Reviewed-by: Rob Herring <robh@kernel.org>
> Reviewed-by: Thierry Reding <treding@nvidia.com>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Saravana Kannan <saravanak@google.com>

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.

Guenter

---
# bad: [07f7e57c63aaa2afb4ea31edef05e08699a63a00] Add linux-next specific files for 20210212
# good: [92bf22614b21a2706f4993b278017e437f7785b3] Linux 5.11-rc7
git bisect start 'HEAD' 'v5.11-rc7'
# good: [987d576a592082b8e0e499990236f49ad655f5dc] Merge remote-tracking branch 'crypto/master'
git bisect good 987d576a592082b8e0e499990236f49ad655f5dc
# good: [e254726a51e0440c05eb4606215772c34b77a53f] Merge remote-tracking branch 'spi/for-next'
git bisect good e254726a51e0440c05eb4606215772c34b77a53f
# bad: [309b7dce497b1ce820b2afb13a19b0ad39b23a4a] Merge remote-tracking branch 'char-misc/char-misc-next'
git bisect bad 309b7dce497b1ce820b2afb13a19b0ad39b23a4a
# good: [5c45f9ce2ad5c4abf79baf114e42620da77c84fe] Merge remote-tracking branch 'chrome-platform/for-next'
git bisect good 5c45f9ce2ad5c4abf79baf114e42620da77c84fe
# bad: [b45d849cd57bf11d1824f68d92404ceea1293886] Merge remote-tracking branch 'usb/usb-next'
git bisect bad b45d849cd57bf11d1824f68d92404ceea1293886
# good: [89451aabea5f91a6c1b6dc4c52cac4caffecbc8a] Merge tag 'tag-ib-usb-typec-chrome-platform-cros-ec-typec-clear-pd-discovery-events-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux into usb-next
git bisect good 89451aabea5f91a6c1b6dc4c52cac4caffecbc8a
# good: [43861d29c0810a70792bf69d37482efb7bb6677d] USB: quirks: sort quirk entries
git bisect good 43861d29c0810a70792bf69d37482efb7bb6677d
# good: [08f4a6b903369ee0147b557931b7075c17e015f6] dt-bindings: usb: dwc3: add description for rk3328
git bisect good 08f4a6b903369ee0147b557931b7075c17e015f6
# bad: [1753c4d1edbcf1b35e585ff76777d09434344c8f] of: property: Don't add links to absent suppliers
git bisect bad 1753c4d1edbcf1b35e585ff76777d09434344c8f
# good: [072a51be8ecfb84e15b27b7f80a601560f386788] Merge 5.11-rc5 into driver-core-next
git bisect good 072a51be8ecfb84e15b27b7f80a601560f386788
# bad: [4731210c09f5977300f439b6c56ba220c65b2348] gpiolib: Bind gpio_device to a driver to enable fw_devlink=on by default
git bisect bad 4731210c09f5977300f439b6c56ba220c65b2348
# bad: [4044b2fcfb2048a256529ecbd869b43713982006] drivers: base: change 'driver_create_groups' to 'driver_add_groups' in printk
git bisect bad 4044b2fcfb2048a256529ecbd869b43713982006
# bad: [4104ca776ba38d81bd6610256d3b0d7e6a058067] of: property: Add fw_devlink support for interrupts
git bisect bad 4104ca776ba38d81bd6610256d3b0d7e6a058067
# good: [e13f5b7a130f7b6d4d34be27a87393890b5ee2ba] of: property: Add fw_devlink support for "gpio" and "gpios" binding
git bisect good e13f5b7a130f7b6d4d34be27a87393890b5ee2ba
# first bad commit: [4104ca776ba38d81bd6610256d3b0d7e6a058067] of: property: Add fw_devlink support for interrupts