Hi Chris,
On Mon, 29 Jul 2024 at 09:44, Chris Webb chris@arachsys.com wrote:
Simon Glass sjg@chromium.org wrote:
We cannot probe devices when they are bound since it breaks the ordering of driver model.
From your trace it looks like everything is happening after relocation. I can't quite see what is actually going wrong. But if you look at dm_init_and_scan(), it does the probe at the end, immediately after all devices have been bound. So it should do what you want.
Is the GPIO device not being bound? There is something strange here.
Hi Simon, many thanks for your follow up. Yes I wasn't convinced the patch was the correct fix (hence the RFC) but posted as it was one of the two ways I found to make gpio-hog work, the other being adding a .bind function in U_BOOT_DRIVER(mt7981_pinctrl) like
static int mtk_pinctrl_mt7981_bind(struct udevice *dev) { dev_or_flags(dev, DM_FLAG_PROBE_AFTER_BIND); return 0; }to force a probe after bind in the parent pinctrl device. I was hoping someone with more clue than me might go 'Aha! This is just...' :)
?
The device I tested on has been deployed but I can probably get it back for a bit and resolder a serial console on to test again if that would be helpful. Are there other significant places I should be adding some traces that would make the problem clearer?
Is it significant/relevant that the gpio device is a child of the pinctrl device in the mt7981 device tree?
I think the gpio device must be getting bound, because otherwise my trace in gpio_post_bind() wouldn't get called at all, but perhaps it's bound too late somehow?
Well, yes, mt7981_pinctrl is wrong since it is not actually binding the GPIO devices until it itself is probed. It should do it when it is bound.
Better still, those GPIO devices should be in the devicetree and bound automatically by driver model. But, sigh, I see that there is no compatible string in the gpio subnode of pinctrl@11d00000. It should really have one and avoid all this pointless code and problems.
mtk_pinctrl_common_probe() is misnamed, as it actually binds and then probes.
So (unless Linux allows a patch to add a compatible string) it needs a new mtk_pinctrl_common_bind() (called from mtk_pinctrl_mt7981_bind()) which calls mtk_gpiochip_register(). Then you won't need to add your dev_or_flags() into mtk_pinctrl_mt7981_bind().
Regards, Simon