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Date: Tue, 30 Jun 2020 20:14:37 -0700 From: Florian Fainelli <f.fainelli@...il.com> To: Mark Tomlinson <Mark.Tomlinson@...iedtelesis.co.nz>, "ray.jui@...adcom.com" <ray.jui@...adcom.com>, "bcm-kernel-feedback-list@...adcom.com" <bcm-kernel-feedback-list@...adcom.com>, "linus.walleij@...aro.org" <linus.walleij@...aro.org>, "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>, "sbranden@...adcom.com" <sbranden@...adcom.com>, "rjui@...adcom.com" <rjui@...adcom.com> Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] pinctrl: initialise nsp-mux earlier. On 6/30/2020 7:23 PM, Mark Tomlinson wrote: > On Tue, 2020-06-30 at 15:08 -0700, Ray Jui wrote: >> May I know which GPIO driver you are referring to on NSP? Both the iProc >> GPIO driver and the NSP GPIO driver are initialized at the level of >> 'arch_initcall_sync', which is supposed to be after 'arch_initcall' used >> here in the pinmux driver > > Sorry, it looks like I made a mistake in my testing (or I was lucky), > and this patch doesn't fix the issue. What is happening is: > 1) nsp-pinmux driver is registered (arch_initcall). > 2) nsp-gpio-a driver is registered (arch_initcall_sync). > 3) of_platform_default_populate_init() is called (also at level > arch_initcall_sync), which scans the device tree, adds the nsp-gpio-a > device, runs its probe, and this returns -EPROBE_DEFER with the error > message. > 4) Only now nsp-pinmux device is probed. > > Changing the 'arch_initcall_sync' to 'device_initcall' in nsp-gpio-a > ensures that the pinmux is probed first since > of_platform_default_populate_init() will be called between the two > register calls, and the error goes away. Is this change acceptable as a > solution? If probe deferral did not work, certainly but it sounds like this is being done just for the sake of eliminating a round of probe deferral, is there a functional problem this is fixing? > >>> though the probe will succeed when the driver is re-initialised, the >>> error can be scary to end users. To fix this, change the time the >> >> Scary to end users? I don't know about that. -EPROBE_DEFER was >> introduced exactly for this purpose. Perhaps users need to learn what >> -EPROBE_DEFER errno means? > > The actual error message in syslog is: > > kern.err kernel: gpiochip_add_data_with_key: GPIOs 480..511 > (18000020.gpio) failed to register, -517 > > So an end user sees "err" and "failed", and doesn't know what "-517" > means. How about this instead: diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 4fa075d49fbc..10d9d0c17c9e 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1818,9 +1818,10 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, ida_simple_remove(&gpio_ida, gdev->id); err_free_gdev: /* failures here can mean systems won't boot... */ - pr_err("%s: GPIOs %d..%d (%s) failed to register, %d\n", __func__, - gdev->base, gdev->base + gdev->ngpio - 1, - gc->label ? : "generic", ret); + if (ret != -EPROBE_DEFER) + pr_err("%s: GPIOs %d..%d (%s) failed to register, %d\n", + __func__, gdev->base, gdev->base + gdev->ngpio - 1, + gc->label ? : "generic", ret); kfree(gdev); return ret; } -- Florian
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