[patchset 0/3 -2.6.18-rc1] pc8736x_gpio: fix re-modprobe errors

Jim Cromie
2006-07-08T14:09:55Z

Linus Torvalds wrote:
> Ok,
> the merge window for 2.6.18 is closed, and -rc1 is out there (git trees
>

The new pc8736x_gpio driver has at least 1 bug, which manifests when
module is rmmod'd then re-modprobe'd. This 3 part patchset addresses it
as follows:

1 - add constant defines - preparatory patch

- adds #define CONSTs for max-pin, gpio-addr-range (for reserving region)
- fix wrong max-pin check in gpio_open()
- add 'Winbond' to module description: NSC sold the product, Winbond
has us / lm-sensors

pc-const-decl - define several symbolic constants
pc-open-const - use reduced max-pin to what hardware supports
pc-req-region-const - can wait, but why
pc-mod-desc-add-winbond -

since this is just preparatory work, it still exhibits the bug:

soekris:~# rmmod pc8736x_gpio
soekris:~# modprobe pc8736x_gpio
[ 498.970735] kobject_add failed for pc8736x_gpio.0 with -EEXIST, don't
try to register things with the same name in the same directory.
[ 498.985568] [<c0102fbf>] show_trace_log_lvl+0x54/0xfd
[ 498.991398] [<c0103fba>] show_trace+0xd/0x10
[ 498.996629] [<c0103fd4>] dump_stack+0x17/0x1b
[ 499.001759] [<c01d1c6a>] kobject_add+0x17d/0x19c
[ 499.014898] [<c0203362>] device_add+0x7a/0x2cc
[ 499.029917] [<c020616d>] platform_device_add+0xdc/0x10c
[ 499.045902] [<c8820028>] pc8736x_gpio_init+0x28/0x258 [pc8736x_gpio]
[ 499.053212] [<c012a67a>] sys_init_module+0x1381/0x1463
[ 499.061327] [<c0102657>] syscall_call+0x7/0xb
FATAL: Error inserting pc8736x_gpio
(/lib/modules/2.6.18-rc1-jimc-sk/kernel/drivers/char/pc8736x_gpio.ko):
No such device

2 - pc-init-fix-undo-region-rollup

this patch fixes module-init-func by repairing usage of
platform_device_del/put in module-exit-func,
ie it imitates Ingo's 'mishaps' patch, which fixed the
module-init-func's undo handling.
Also fixes lack of release_region to undo the earlier registration.

Also included:
- add include <linux/cdev.h> - needed by next patches
and cuz theyre within the diff-context-window:
- remove include <linux/config.h> everyone's doing it
- copyright updates - current date is 'wrong'

the patch fixes the above bug, reducing it to a different one; (which is
fixed by 3rd patch)

soekris:~# rmmod pc8736x_gpio
soekris:~# modprobe pc8736x_gpio
[ 283.618997] platform pc8736x_gpio.0: NatSemi pc8736x GPIO Driver
Initializing
[ 283.626534] platform pc8736x_gpio.0: GPIO ioport 6600 reserved
[ 283.633319] platform pc8736x_gpio.0: register-chrdev failed: -16
FATAL: Error inserting pc8736x_gpio
(/lib/modules/2.6.18-rc1-jimc-sk/kernel/drivers/char/pc8736x_gpio.ko):
Device or resource busy

3 - pc-init-fix-chrdev-region-rollup

- Switch from register_chrdev() to (register|alloc)_chrdev_region().

- use a cdev. This was intended for original patchset, but was overlooked.
We use a single cdev for all pins (minor device-numbers), as gleaned
from cs5535_gpio,
and in contrast to whats currently done in scx200_gpio (which I'll fix soon)

By some reasoning, this patch should have been combined with patch 2;
the fixes
are to the same 2 mod-init/exit functions, and both touch cdevs,
regions, etc.
Despite this, I separated them (incompletely). I'll combine them if
thats better..

Given that this is a brand new driver, can I assume a bit more latitude to
clean up and normalize the code ? For example, s/DEVNAME/DRVNAME/
would improve consistency with other drivers. The scx200_gpio driver
could also
stand some improvements; a single cdev, and same DRVNAME normalization.

Whats the right way to mark this as (NEW/EXPERIMENTAL) ?
Is either appropriate for a reworked / existing driver (scx200_gpio)

cc'g AKPM since (I think) he pushed this driver to mainline.

thanks
Jim Cromie