On Mon, Feb 8, 2021 at 11:55 PM Stephen Boyd [off-list ref] wrote:

Quoting Saravana Kannan (2021-01-28 09:01:41)

quoted

On Thu, Jan 28, 2021 at 2:45 AM Tudor Ambarus
[off-list ref] wrote:

quoted

The sama5d2 requires the clock provider initialized before timers.
We can't use a platform driver for the sama5d2-pmc driver, as the
platform_bus_init() is called later on, after time_init().

As fw_devlink considers only devices, it does not know that the
pmc is ready. Hence probing of devices that depend on it fail:
probe deferral - supplier f0014000.pmc not ready

Fix this by setting the OF_POPULATED flag for the sama5d2_pmc
device node after successful setup. This will make
of_link_to_phandle() ignore the sama5d2_pmc device node as a
dependency, and consumer devices will be probed again.

Fixes: e590474768f1cc04 ("driver core: Set fw_devlink=on by default")
Signed-off-by: Tudor Ambarus <redacted>
---
I'll be out of office, will check the rest of the at91 SoCs
at the begining of next week.

 drivers/clk/at91/sama5d2.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/clk/at91/sama5d2.c b/drivers/clk/at91/sama5d2.c
index 9a5cbc7cd55a..5eea2b4a63dd 100644
--- a/drivers/clk/at91/sama5d2.c
+++ b/drivers/clk/at91/sama5d2.c

@@ -367,6 +367,8 @@ static void __init sama5d2_pmc_setup(struct device_node *np)

        of_clk_add_hw_provider(np, of_clk_hw_pmc_get, sama5d2_pmc);

+       of_node_set_flag(np, OF_POPULATED);
+
        return;

Hi Tudor,

Thanks for looking into this.

I already accounted for early clocks like this when I designed
fw_devlink. Each driver shouldn't need to set OF_POPULATED.
drivers/clk/clk.c already does this for you.

I think the problem is that your driver is using
CLK_OF_DECLARE_DRIVER() instead of CLK_OF_DECLARE(). The comments for
CLK_OF_DECLARE_DRIVER() says:
/*
 * Use this macro when you have a driver that requires two initialization
 * routines, one at of_clk_init(), and one at platform device probe
 */

In your case, you are explicitly NOT having a driver bind to this
clock later. So you shouldn't be using CLK_OF_DECLARE() instead.

I see

drivers/power/reset/at91-sama5d2_shdwc.c:       { .compatible = "atmel,sama5d2-pmc" },

so isn't that the driver that wants to bind to the same device node
again? First at of_clk_init() time here and then second for the reset
driver?

You are right. I assumed that when Tudor was setting OF_POPULATED,
they didn't want to create a struct device and they knew it was right
for their platform.

However...
$ git grep "atmel,sama5d2-pmc"
arch/arm/boot/dts/sama5d2.dtsi:                         compatible =
"atmel,sama5d2-pmc", "syscon";
arch/arm/mach-at91/pm.c:        { .compatible = "atmel,sama5d2-pmc",
.data = &pmc_infos[1] },
drivers/clk/at91/pmc.c: { .compatible = "atmel,sama5d2-pmc" },
drivers/clk/at91/sama5d2.c:CLK_OF_DECLARE_DRIVER(sama5d2_pmc,
"atmel,sama5d2-pmc", sama5d2_pmc_setup);
drivers/power/reset/at91-sama5d2_shdwc.c:       { .compatible =
"atmel,sama5d2-pmc" },

Geez! How many drivers are there for this one device. Clearly not all
of them are going to bind. But I'm not going to dig into this. You can
reject this patch. I expect this series [1] to take care of the issue
Tudor was trying to fix.

Tudor,

Want to give this series [1] a shot?

[1] - https://lore.kernel.org/lkml/20210205222644.2357303-1-saravanak@google.com/ (local)
-Saravana

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