Re: [PATCH v2 0/3] Make fw_devlink=on more forgiving

[Tudor.Ambarus]

Hi, Saravana,

On 2/2/21 6:33 AM, Saravana Kannan wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> This patch series solves two general issues with fw_devlink=on
> 
> Patch 1/3 and 3/3 addresses the issue of firmware nodes that look like
> they'll have struct devices created for them, but will never actually
> have struct devices added for them. For example, DT nodes with a
> compatible property that don't have devices added for them.
> 
> Patch 2/2 address (for static kernels) the issue of optional suppliers
> that'll never have a driver registered for them. So, if the device could
> have probed with fw_devlink=permissive with a static kernel, this patch
> should allow those devices to probe with a fw_devlink=on. This doesn't
> solve it for the case where modules are enabled because there's no way
> to tell if a driver will never be registered or it's just about to be
> registered. I have some other ideas for that, but it'll have to come
> later thinking about it a bit.
> 
> Marek, Geert,
> 
> I don't expect v2 to do any better for your cases.
> 
> This series not making any difference for Marek is still a mystery to
> me. I guess one of the consumers doesn't take too well to its probe (and
> it's consumers' probe) being delayed till late_initcall(). I'll continue
> looking into it.
> 
> Marc,
> 
> This v2 should do better than v1 with gpiolib stub driver reverted. I
> forgot to take care of the case where more suppliers could link after I
> went and deleted some of the links. v2 handles that now.
> 
> Tudor,
> 
> You should still make the clock driver fix (because it's a bug), but I
> think this series will fix your issue too (even without the clock driver
> fix). Can you please give this a shot?
> 

Did the following tests (using sama5_defconfig and at91-sama5d2_xplained.dts):
1/ modular kernel with your v2 on top of next-20210202, and without the clock
driver fix: the problem persists.

2/ static kernel with your v2 on top of next-20210202, and without the clock
driver fix: the problem persists. Comparing to the previous test, I see that
the links to pmc are dropped. I can see the following only with early printk
enabled:
platform fc008000.serial: Dropping the link to f0014000.pmc
But later on, the serial still gets deferred waiting for the dma controller
this time:
platform f8020000.serial: probe deferral - supplier f0010000.dma-controller not ready
I'll check what happens in the dma-controller.

3/ modular kernel with your v2 and the clock driver fix on top of next-20210202:
I can boot the board and I have access to the console. I still have some
probe deferrals that I need to check:
root@sama5d2-xplained-sd:~# dmesg | grep -i defer
[    4.335625] platform b0000000.sdio-host: probe deferral - wait for supplier pmic@5b
[    4.474559] platform fc030000.adc: probe deferral - wait for supplier pmic@5b
[    4.884315] calling  deferred_probe_initcall+0x0/0xd8 @ 1
[    4.889206] platform fc030000.adc: probe deferral - wait for supplier pmic@5b
[    5.139447] initcall deferred_probe_initcall+0x0/0xd8 returned 0 after 245132 usecs
root@sama5d2-xplained-sd:~# dmesg | grep -i linked
[    4.916342] platform fc030000.adc: Linked as a consumer to 0-005b
[    4.921298] platform b0000000.sdio-host: Linked as a consumer to 0-005b
[    4.926817] i2c 0-005b: Linked as a sync state only consumer to fc038000.pinctrl
[    4.990246] platform act8945a-charger: Linked as a consumer to fc038000.pinctrl
[    5.078488] at24 1-0054: Linked as a consumer to regulator.0
[    5.111533] at91-sama5d2_adc fc030000.adc: Linked as a consumer to regulator.5
[    5.118969] sdhci-at91 b0000000.sdio-host: Linked as a consumer to regulator.3
root@sama5d2-xplained-sd:~# dmesg | grep -i drop
[    5.014026] act8945a 0-005b: Dropping the link to fc038000.pinctrl

4/ static kernel with your v2 and the clock driver fix on top of next-20210202:
I can boot the board and I have access to the console. The probe deferrals are the
same as in test 3/.

Cheers,
ta