Hi Saravana,

On Fri, Feb 5, 2021 at 11:06 AM Saravana Kannan [off-list ref] wrote:

On Fri, Feb 5, 2021 at 12:06 AM Geert Uytterhoeven [off-list ref] wrote:

quoted

On Fri, Feb 5, 2021 at 8:38 AM Marek Szyprowski
[off-list ref] wrote:

quoted

On 04.02.2021 22:31, Saravana Kannan wrote:

quoted

On Thu, Feb 4, 2021 at 3:52 AM Marek Szyprowski
[off-list ref] wrote:

quoted

On 21.01.2021 23:57, Saravana Kannan wrote:

quoted

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 <redacted>
Reviewed-by: Linus Walleij <redacted>
Signed-off-by: Saravana Kannan <redacted>

This patch landed some time ago in linux-next as commit 4104ca776ba3
("of: property: Add fw_devlink support for interrupts"). It breaks MMC
host controller operation on ARM Juno R1 board (the mmci@50000 device
defined in arch/arm64/boot/dts/arm/juno-motherboard.dtsi). I didn't

I grepped around and it looks like the final board file is this or
whatever includes it?
arch/arm64/boot/dts/arm/juno-base.dtsi

The final board file is arch/arm64/boot/dts/arm/juno-r1.dts

quoted

This patch just finds the interrupt-parent and then tries to use that
as a supplier if "interrupts" property is listed. But the only
interrupt parent I can see is:
         gic: interrupt-controller@2c010000 {
                 compatible = "arm,gic-400", "arm,cortex-a15-gic";

And the driver uses IRQCHIP_DECLARE() and hence should be pretty much
a NOP since those suppliers are never devices and are ignored.
$ git grep "arm,gic-400" -- drivers/
drivers/irqchip/irq-gic.c:IRQCHIP_DECLARE(gic_400, "arm,gic-400", gic_of_init);

This doesn't make any sense. Am I looking at the right files? Am I
missing something?

Okay, I've added displaying a list of deferred devices when mounting
rootfs fails and got following items:

Deferred devices:
18000000.ethernet        platform: probe deferral - supplier
bus@8000000:motherboard-bus not ready
1c050000.mmci    amba: probe deferral - supplier
bus@8000000:motherboard-bus not ready
1c1d0000.gpio    amba: probe deferral - supplier
bus@8000000:motherboard-bus not ready
2b600000.iommu   platform: probe deferral - wait for supplier
scpi-power-domains
7ff50000.hdlcd   platform: probe deferral - wait for supplier scpi-clk
7ff60000.hdlcd   platform: probe deferral - wait for supplier scpi-clk
1c060000.kmi     amba: probe deferral - supplier
bus@8000000:motherboard-bus not ready
1c070000.kmi     amba: probe deferral - supplier
bus@8000000:motherboard-bus not ready
1c170000.rtc     amba: probe deferral - supplier
bus@8000000:motherboard-bus not ready
1c0f0000.wdt     amba: probe deferral - supplier
bus@8000000:motherboard-bus not ready
gpio-keys
Kernel panic - not syncing: VFS: Unable to mount root fs on
unknown-block(0,0)

I don't see the 'bus@8000000:motherboard-bus' on the deferred devices
list, so it looks that device core added a link to something that is not
a platform device...

Probe deferred devices (even platform devices) not showing up in that
list is not unusual. That's because devices end up on that list only
after a driver for them is matched and then it fails.

quoted

Lemme guess: bus@8000000 is a simple bus, but it has an
interrupt-map, and the devlink code doesn't follow the mapping?

No, what's happening is that (and this is something I just learned)
that if a parent has an "#interrupt-cells" property, it becomes your
interrupt parent. In this case, the motherboard-bus (still a platform
device) is the parent, but it never probes (because it's simple-bus
and "arm,vexpress,v2p-p1"). But it becomes the interrupt parent. And
this mmci device is marked as a consumer of this bus (while still a
grand-child). Yeah, I'm working on patches (multiple rewrites) to take
care of cases like this.

One more reason to scrap the different handling of "simple-bus" and
"simple-pm-bus", and use drivers/bus/simple-pm-bus.c, which is a
platform device driver, for both? (like I originally intended ;-)

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