On 20/02/2021 11:58, Sean Young wrote:
> Hi Hans,
>
> Thank you for writing this patch.
>
> On Thu, Feb 18, 2021 at 05:13:08PM +0100, Hans Verkuil wrote:
>> The rc-cec keymap is unusual in that it can't be built as a module,
>> instead it is registered directly in rc-main.c if CONFIG_MEDIA_CEC_RC
>> is set. This is because it can be called from drm_dp_cec_set_edid() via
>> cec_register_adapter() in an asynchronous context, and it is not
>> allowed to use request_module() to load rc-cec.ko in that case. Trying to
>> do so results in a 'WARN_ON_ONCE(wait && current_is_async())'.
>>
>> Since this keymap is only used if CONFIG_MEDIA_CEC_RC is set, we
>> just compile this keymap into the rc-core module and never as a
>> separate module.
>>
>> Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
>> Fixes: 2c6d1fffa1d9 (drm: add support for DisplayPort CEC-Tunneling-over-AUX)
>> Reported-by: Hans de Goede <hdegoede@xxxxxxxxxx>
>> ---
>> Sean, I tested this both with RC_CORE=y and =m.
>>
>> It looks reasonably clean to me, but I am not sure if this affects v4l-utils
>> as well. Let me know what you think.
>>
>> Regards,
>>
>> Hans
>> ---
>> diff --git a/drivers/media/rc/Makefile b/drivers/media/rc/Makefile
>> index 5bb2932ab119..ff6a8fc4c38e 100644
>> --- a/drivers/media/rc/Makefile
>> +++ b/drivers/media/rc/Makefile
>> @@ -5,6 +5,7 @@ obj-y += keymaps/
>> obj-$(CONFIG_RC_CORE) += rc-core.o
>> rc-core-y := rc-main.o rc-ir-raw.o
>> rc-core-$(CONFIG_LIRC) += lirc_dev.o
>> +rc-core-$(CONFIG_MEDIA_CEC_RC) += keymaps/rc-cec.o
>> rc-core-$(CONFIG_BPF_LIRC_MODE2) += bpf-lirc.o
>> obj-$(CONFIG_IR_NEC_DECODER) += ir-nec-decoder.o
>> obj-$(CONFIG_IR_RC5_DECODER) += ir-rc5-decoder.o
>> diff --git a/drivers/media/rc/keymaps/Makefile b/drivers/media/rc/keymaps/Makefile
>> index b252a1d2ebd6..cc6662e1903f 100644
>> --- a/drivers/media/rc/keymaps/Makefile
>> +++ b/drivers/media/rc/keymaps/Makefile
>> @@ -21,7 +21,6 @@ obj-$(CONFIG_RC_MAP) += rc-adstech-dvb-t-pci.o \
>> rc-behold.o \
>> rc-behold-columbus.o \
>> rc-budget-ci-old.o \
>> - rc-cec.o \
>> rc-cinergy-1400.o \
>> rc-cinergy.o \
>> rc-d680-dmb.o \
>
> This is a great idea. If rc-core is built as a module, the cec keymap is
> included in the module, and if cec-rc is not enabled then it is not built
> at all.
>
>> diff --git a/drivers/media/rc/keymaps/rc-cec.c b/drivers/media/rc/keymaps/rc-cec.c
>> index 3e3bd11092b4..068e22aeac8c 100644
>> --- a/drivers/media/rc/keymaps/rc-cec.c
>> +++ b/drivers/media/rc/keymaps/rc-cec.c
>> @@ -1,5 +1,15 @@
>> // SPDX-License-Identifier: GPL-2.0-or-later
>> /* Keytable for the CEC remote control
>> + *
>> + * This keymap is unusual in that it can't be built as a module,
>> + * instead it is registered directly in rc-main.c if CONFIG_MEDIA_CEC_RC
>> + * is set. This is because it can be called from drm_dp_cec_set_edid() via
>> + * cec_register_adapter() in an asynchronous context, and it is not
>> + * allowed to use request_module() to load rc-cec.ko in that case.
>> + *
>> + * Since this keymap is only used if CONFIG_MEDIA_CEC_RC is set, we
>> + * just compile this keymap into the rc-core module and never as a
>> + * separate module.
>> *
>> * Copyright (c) 2015 by Kamil Debski
>> */
>> @@ -152,7 +162,7 @@ static struct rc_map_table cec[] = {
>> /* 0x77-0xff: Reserved */
>> };
>>
>> -static struct rc_map_list cec_map = {
>> +struct rc_map_list cec_map = {
>> .map = {
>> .scan = cec,
>> .size = ARRAY_SIZE(cec),
>> @@ -160,19 +170,3 @@ static struct rc_map_list cec_map = {
>> .name = RC_MAP_CEC,
>> }
>> };
>> -
>> -static int __init init_rc_map_cec(void)
>> -{
>> - return rc_map_register(&cec_map);
>> -}
>> -
>> -static void __exit exit_rc_map_cec(void)
>> -{
>> - rc_map_unregister(&cec_map);
>> -}
>> -
>> -module_init(init_rc_map_cec);
>> -module_exit(exit_rc_map_cec);
>> -
>> -MODULE_LICENSE("GPL");
>> -MODULE_AUTHOR("Kamil Debski");
>> diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
>> index 1fd62c1dac76..4768b1e9ffd1 100644
>> --- a/drivers/media/rc/rc-main.c
>> +++ b/drivers/media/rc/rc-main.c
>> @@ -163,6 +163,10 @@ static struct rc_map_list empty_map = {
>> }
>> };
>>
>> +#ifdef CONFIG_MEDIA_CEC_RC
>> +extern struct rc_map_list cec_map;
>> +#endif
>> +
>> /**
>> * scancode_to_u64() - converts scancode in &struct input_keymap_entry
>> * @ke: keymap entry containing scancode to be converted.
>> @@ -2069,6 +2073,9 @@ static int __init rc_core_init(void)
>>
>> led_trigger_register_simple("rc-feedback", &led_feedback);
>> rc_map_register(&empty_map);
>> +#ifdef CONFIG_MEDIA_CEC_RC
>> + rc_map_register(&cec_map);
>> +#endif
>>
>> return 0;
>> }
>> @@ -2078,6 +2085,9 @@ static void __exit rc_core_exit(void)
>> lirc_dev_exit();
>> class_unregister(&rc_class);
>> led_trigger_unregister_simple(led_feedback);
>> +#ifdef CONFIG_MEDIA_CEC_RC
>> + rc_map_register(&cec_map);
Oops, this should be rc_map_unregister()!
>> +#endif
>> rc_map_unregister(&empty_map);
>> }
>
> Now I'm confused. Do we need these changes at all? I've experimented a little
> bit (without the right hardware), and as far as I can make out, just the
> changes to the Kconfig/Makefile should be enough.
If I build with CONFIG_RC_CORE=m, then I get:
CC [M] drivers/media/rc/keymaps/rc-cec.o
LD [M] drivers/media/rc/rc-core.o
ld: drivers/media/rc/keymaps/rc-cec.o: in function `init_rc_map_cec':
/home/hans/work/src/v4l/media-git/drivers/media/rc/keymaps/rc-cec.c:165: multiple definition of `init_module';
drivers/media/rc/rc-main.o:/home/hans/work/src/v4l/media-git/drivers/media/rc/rc-main.c:2056: first defined here
ld: drivers/media/rc/keymaps/rc-cec.o: in function `exit_rc_map_cec':
/home/hans/work/src/v4l/media-git/drivers/media/rc/keymaps/rc-cec.c:171: multiple definition of `cleanup_module';
drivers/media/rc/rc-main.o:/home/hans/work/src/v4l/media-git/drivers/media/rc/rc-main.c:2078: first defined here
Which makes sense since now there are two module_init/exit entries.
It does work if CONFIG_RC_CORE=y, but not for =m.
Unless I am missing something, this is the right approach.
I'll post a v2 to fix the unregister issue.
Regards,
Hans
