diff mbox series

[1/3] wifi: mt76: mt7915: remove VHT160 capability on MT7915

Message ID 20230726091704.25795-1-nbd@nbd.name
State New
Headers show
Series [1/3] wifi: mt76: mt7915: remove VHT160 capability on MT7915 | expand

Commit Message

Felix Fietkau July 26, 2023, 9:17 a.m. UTC
The IEEE80211_VHT_CAP_EXT_NSS_BW value already indicates support for half-NSS
160 MHz support, so it is wrong to also advertise full 160 MHz support.

Fixes: c2f73eacee3b ("wifi: mt76: mt7915: add back 160MHz channel width support for MT7915")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 drivers/net/wireless/mediatek/mt76/mt7915/init.c | 1 -
 1 file changed, 1 deletion(-)

Comments

Oleksandr Natalenko Sept. 21, 2023, 5:02 a.m. UTC | #1
Hello Felix.

On středa 26. července 2023 11:17:02 CEST Felix Fietkau wrote:
> The IEEE80211_VHT_CAP_EXT_NSS_BW value already indicates support for half-NSS
> 160 MHz support, so it is wrong to also advertise full 160 MHz support.
> 
> Fixes: c2f73eacee3b ("wifi: mt76: mt7915: add back 160MHz channel width support for MT7915")
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>  drivers/net/wireless/mediatek/mt76/mt7915/init.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> index ee976657bfc3..78552f10b377 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> @@ -414,7 +414,6 @@ mt7915_init_wiphy(struct mt7915_phy *phy)
>  			if (!dev->dbdc_support)
>  				vht_cap->cap |=
>  					IEEE80211_VHT_CAP_SHORT_GI_160 |
> -					IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ |
>  					FIELD_PREP(IEEE80211_VHT_CAP_EXT_NSS_BW_MASK, 1);
>  		} else {
>  			vht_cap->cap |=
> 

For some reason this got backported into the stable kernel:

```
$ git log --oneline v6.5.2..v6.5.4 -- drivers/net/wireless/mediatek/mt76/mt7915/
c43017fbebcc3 wifi: mt76: mt7915: fix power-limits while chan_switch
edb1afe042c74 wifi: mt76: mt7915: fix tlv length of mt7915_mcu_get_chan_mib_info
9ec0dec0baea3 wifi: mt76: mt7915: remove VHT160 capability on MT7915
0e61f73e6ebc0 wifi: mt76: mt7915: fix capabilities in non-AP mode
6bce28ce28390 wifi: mt76: mt7915: fix command timeout in AP stop period
7af917d4864c6 wifi: mt76: mt7915: rework tx bytes counting when WED is active
feae00c6468ce wifi: mt76: mt7915: rework tx packets counting when WED is active
70bbcc4ad6544 wifi: mt76: mt7915: fix background radar event being blocked
```

and this broke my mt7915-based AP.

However, if I remove `[VT160]` capability from the hostapd config, things go back to normal. It does seem that 160 MHz still works even.

Is this expected?

Please check.

Thanks.
Greg KH Sept. 21, 2023, 7:19 a.m. UTC | #2
On Thu, Sep 21, 2023 at 07:02:41AM +0200, Oleksandr Natalenko wrote:
> Hello Felix.
> 
> On středa 26. července 2023 11:17:02 CEST Felix Fietkau wrote:
> > The IEEE80211_VHT_CAP_EXT_NSS_BW value already indicates support for half-NSS
> > 160 MHz support, so it is wrong to also advertise full 160 MHz support.
> > 
> > Fixes: c2f73eacee3b ("wifi: mt76: mt7915: add back 160MHz channel width support for MT7915")
> > Signed-off-by: Felix Fietkau <nbd@nbd.name>
> > ---
> >  drivers/net/wireless/mediatek/mt76/mt7915/init.c | 1 -
> >  1 file changed, 1 deletion(-)
> > 
> > diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> > index ee976657bfc3..78552f10b377 100644
> > --- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> > +++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> > @@ -414,7 +414,6 @@ mt7915_init_wiphy(struct mt7915_phy *phy)
> >  			if (!dev->dbdc_support)
> >  				vht_cap->cap |=
> >  					IEEE80211_VHT_CAP_SHORT_GI_160 |
> > -					IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ |
> >  					FIELD_PREP(IEEE80211_VHT_CAP_EXT_NSS_BW_MASK, 1);
> >  		} else {
> >  			vht_cap->cap |=
> > 
> 
> For some reason this got backported into the stable kernel:
> 
> ```
> $ git log --oneline v6.5.2..v6.5.4 -- drivers/net/wireless/mediatek/mt76/mt7915/
> c43017fbebcc3 wifi: mt76: mt7915: fix power-limits while chan_switch
> edb1afe042c74 wifi: mt76: mt7915: fix tlv length of mt7915_mcu_get_chan_mib_info
> 9ec0dec0baea3 wifi: mt76: mt7915: remove VHT160 capability on MT7915
> 0e61f73e6ebc0 wifi: mt76: mt7915: fix capabilities in non-AP mode
> 6bce28ce28390 wifi: mt76: mt7915: fix command timeout in AP stop period
> 7af917d4864c6 wifi: mt76: mt7915: rework tx bytes counting when WED is active
> feae00c6468ce wifi: mt76: mt7915: rework tx packets counting when WED is active
> 70bbcc4ad6544 wifi: mt76: mt7915: fix background radar event being blocked
> ```
> 
> and this broke my mt7915-based AP.
> 
> However, if I remove `[VT160]` capability from the hostapd config, things go back to normal. It does seem that 160 MHz still works even.
> 
> Is this expected?

Is your device also broken in 6.6-rc2?

thanks,

greg k-h
Oleksandr Natalenko Sept. 21, 2023, 4:03 p.m. UTC | #3
Hello.

On čtvrtek 21. září 2023 9:19:58 CEST Greg Kroah-Hartman wrote:
> On Thu, Sep 21, 2023 at 07:02:41AM +0200, Oleksandr Natalenko wrote:
> > Hello Felix.
> > 
> > On středa 26. července 2023 11:17:02 CEST Felix Fietkau wrote:
> > > The IEEE80211_VHT_CAP_EXT_NSS_BW value already indicates support for half-NSS
> > > 160 MHz support, so it is wrong to also advertise full 160 MHz support.
> > > 
> > > Fixes: c2f73eacee3b ("wifi: mt76: mt7915: add back 160MHz channel width support for MT7915")
> > > Signed-off-by: Felix Fietkau <nbd@nbd.name>
> > > ---
> > >  drivers/net/wireless/mediatek/mt76/mt7915/init.c | 1 -
> > >  1 file changed, 1 deletion(-)
> > > 
> > > diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> > > index ee976657bfc3..78552f10b377 100644
> > > --- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> > > +++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> > > @@ -414,7 +414,6 @@ mt7915_init_wiphy(struct mt7915_phy *phy)
> > >  			if (!dev->dbdc_support)
> > >  				vht_cap->cap |=
> > >  					IEEE80211_VHT_CAP_SHORT_GI_160 |
> > > -					IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ |
> > >  					FIELD_PREP(IEEE80211_VHT_CAP_EXT_NSS_BW_MASK, 1);
> > >  		} else {
> > >  			vht_cap->cap |=
> > > 
> > 
> > For some reason this got backported into the stable kernel:
> > 
> > ```
> > $ git log --oneline v6.5.2..v6.5.4 -- drivers/net/wireless/mediatek/mt76/mt7915/
> > c43017fbebcc3 wifi: mt76: mt7915: fix power-limits while chan_switch
> > edb1afe042c74 wifi: mt76: mt7915: fix tlv length of mt7915_mcu_get_chan_mib_info
> > 9ec0dec0baea3 wifi: mt76: mt7915: remove VHT160 capability on MT7915
> > 0e61f73e6ebc0 wifi: mt76: mt7915: fix capabilities in non-AP mode
> > 6bce28ce28390 wifi: mt76: mt7915: fix command timeout in AP stop period
> > 7af917d4864c6 wifi: mt76: mt7915: rework tx bytes counting when WED is active
> > feae00c6468ce wifi: mt76: mt7915: rework tx packets counting when WED is active
> > 70bbcc4ad6544 wifi: mt76: mt7915: fix background radar event being blocked
> > ```
> > 
> > and this broke my mt7915-based AP.
> > 
> > However, if I remove `[VT160]` capability from the hostapd config, things go back to normal. It does seem that 160 MHz still works even.
> > 
> > Is this expected?
> 
> Is your device also broken in 6.6-rc2?

Yes, the same behaviour is observed with v6.6-rc2:

```
hostapd[1316]: Configured VHT capability [VHT_CAP_SUPP_CHAN_WIDTH_MASK] exceeds max value supported by the driver (1 > 0)
```

while having `[VT160]` in `vht_capab=`.

Thanks.

> thanks,
> 
> greg k-h
>
Linux regression tracking (Thorsten Leemhuis) Sept. 22, 2023, 11:22 a.m. UTC | #4
[TLDR: I'm adding this report to the list of tracked Linux kernel
regressions; the text you find below is based on a few templates
paragraphs you might have encountered already in similar form.
See link in footer if these mails annoy you.]

On 21.09.23 07:02, Oleksandr Natalenko wrote:
> 
> On středa 26. července 2023 11:17:02 CEST Felix Fietkau wrote:
>> The IEEE80211_VHT_CAP_EXT_NSS_BW value already indicates support for half-NSS
>> 160 MHz support, so it is wrong to also advertise full 160 MHz support.
>>
>> Fixes: c2f73eacee3b ("wifi: mt76: mt7915: add back 160MHz channel width support for MT7915")
>> Signed-off-by: Felix Fietkau <nbd@nbd.name>
>> ---
>>  drivers/net/wireless/mediatek/mt76/mt7915/init.c | 1 -
>>  1 file changed, 1 deletion(-)
>>
>> diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
>> index ee976657bfc3..78552f10b377 100644
>> --- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
>> +++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
>> @@ -414,7 +414,6 @@ mt7915_init_wiphy(struct mt7915_phy *phy)
>>  			if (!dev->dbdc_support)
>>  				vht_cap->cap |=
>>  					IEEE80211_VHT_CAP_SHORT_GI_160 |
>> -					IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ |
>>  					FIELD_PREP(IEEE80211_VHT_CAP_EXT_NSS_BW_MASK, 1);
>>  		} else {
>>  			vht_cap->cap |=
>>
> 
> For some reason this got backported into the stable kernel:
> 
> ```
> $ git log --oneline v6.5.2..v6.5.4 -- drivers/net/wireless/mediatek/mt76/mt7915/
> c43017fbebcc3 wifi: mt76: mt7915: fix power-limits while chan_switch
> edb1afe042c74 wifi: mt76: mt7915: fix tlv length of mt7915_mcu_get_chan_mib_info
> 9ec0dec0baea3 wifi: mt76: mt7915: remove VHT160 capability on MT7915
> 0e61f73e6ebc0 wifi: mt76: mt7915: fix capabilities in non-AP mode
> 6bce28ce28390 wifi: mt76: mt7915: fix command timeout in AP stop period
> 7af917d4864c6 wifi: mt76: mt7915: rework tx bytes counting when WED is active
> feae00c6468ce wifi: mt76: mt7915: rework tx packets counting when WED is active
> 70bbcc4ad6544 wifi: mt76: mt7915: fix background radar event being blocked
> ```
> 
> and this broke my mt7915-based AP.
> 
> However, if I remove `[VT160]` capability from the hostapd config, things go back to normal. It does seem that 160 MHz still works even.
> 
> Is this expected?

Thanks for the report. To be sure the issue doesn't fall through the
cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
tracking bot:

#regzbot ^introduced 3ec5ac12ac8a4e..fe0ea395f0a351
#regzbot title wifi: mt76: mt7915: removal of VHT160 capability broke hostap
#regzbot ignore-activity

This isn't a regression? This issue or a fix for it are already
discussed somewhere else? It was fixed already? You want to clarify when
the regression started to happen? Or point out I got the title or
something else totally wrong? Then just reply and tell me -- ideally
while also telling regzbot about it, as explained by the page listed in
the footer of this mail.

Developers: When fixing the issue, remember to add 'Link:' tags pointing
to the report (the parent of this mail). See page linked in footer for
details.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
That page also explains what to do if mails like this annoy you.
Linux regression tracking (Thorsten Leemhuis) Sept. 29, 2023, 11:26 a.m. UTC | #5
Seems nothing happened since this regression was reported more that a
week ago. From a quick search on lore it seems Felix is not around
currently; thus bringing the other mt76 maintainers in, maybe they can
help out here to get this fixed rather sooner than later, as the culprit
unfortunately made it to various stable trees. Ciao, Thorsten.

On 21.09.23 18:03, Oleksandr Natalenko wrote:
> On čtvrtek 21. září 2023 9:19:58 CEST Greg Kroah-Hartman wrote:
>> On Thu, Sep 21, 2023 at 07:02:41AM +0200, Oleksandr Natalenko wrote:
>>>
>>> On středa 26. července 2023 11:17:02 CEST Felix Fietkau wrote:
>>>> The IEEE80211_VHT_CAP_EXT_NSS_BW value already indicates support for half-NSS
>>>> 160 MHz support, so it is wrong to also advertise full 160 MHz support.
>>>>
>>>> Fixes: c2f73eacee3b ("wifi: mt76: mt7915: add back 160MHz channel width support for MT7915")
>>>> Signed-off-by: Felix Fietkau <nbd@nbd.name>
>>>> ---
>>>>  drivers/net/wireless/mediatek/mt76/mt7915/init.c | 1 -
>>>>  1 file changed, 1 deletion(-)
>>>>
>>>> diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
>>>> index ee976657bfc3..78552f10b377 100644
>>>> --- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
>>>> +++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
>>>> @@ -414,7 +414,6 @@ mt7915_init_wiphy(struct mt7915_phy *phy)
>>>>  			if (!dev->dbdc_support)
>>>>  				vht_cap->cap |=
>>>>  					IEEE80211_VHT_CAP_SHORT_GI_160 |
>>>> -					IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ |
>>>>  					FIELD_PREP(IEEE80211_VHT_CAP_EXT_NSS_BW_MASK, 1);
>>>>  		} else {
>>>>  			vht_cap->cap |=
>>>>
>>>
>>> For some reason this got backported into the stable kernel:
>>>
>>> ```
>>> $ git log --oneline v6.5.2..v6.5.4 -- drivers/net/wireless/mediatek/mt76/mt7915/
>>> c43017fbebcc3 wifi: mt76: mt7915: fix power-limits while chan_switch
>>> edb1afe042c74 wifi: mt76: mt7915: fix tlv length of mt7915_mcu_get_chan_mib_info
>>> 9ec0dec0baea3 wifi: mt76: mt7915: remove VHT160 capability on MT7915
>>> 0e61f73e6ebc0 wifi: mt76: mt7915: fix capabilities in non-AP mode
>>> 6bce28ce28390 wifi: mt76: mt7915: fix command timeout in AP stop period
>>> 7af917d4864c6 wifi: mt76: mt7915: rework tx bytes counting when WED is active
>>> feae00c6468ce wifi: mt76: mt7915: rework tx packets counting when WED is active
>>> 70bbcc4ad6544 wifi: mt76: mt7915: fix background radar event being blocked
>>> ```
>>>
>>> and this broke my mt7915-based AP.
>>>
>>> However, if I remove `[VT160]` capability from the hostapd config, things go back to normal. It does seem that 160 MHz still works even.
>>>
>>> Is this expected?
>>
>> Is your device also broken in 6.6-rc2?
> 
> Yes, the same behaviour is observed with v6.6-rc2:
> 
> ```
> hostapd[1316]: Configured VHT capability [VHT_CAP_SUPP_CHAN_WIDTH_MASK] exceeds max value supported by the driver (1 > 0)
> ```
> 
> while having `[VT160]` in `vht_capab=`.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
If I did something stupid, please tell me, as explained on that page.

#regzbot introduced 3ec5ac12ac8a4e
#regzbot ignore-activity
Nicolas Cavallari Sept. 29, 2023, 12:59 p.m. UTC | #6
On 21/09/2023 07:02, Oleksandr Natalenko wrote:
> Hello Felix.
> 
> On středa 26. července 2023 11:17:02 CEST Felix Fietkau wrote:
>> The IEEE80211_VHT_CAP_EXT_NSS_BW value already indicates support for half-NSS
>> 160 MHz support, so it is wrong to also advertise full 160 MHz support.
>>
>> Fixes: c2f73eacee3b ("wifi: mt76: mt7915: add back 160MHz channel width support for MT7915")
>> Signed-off-by: Felix Fietkau <nbd@nbd.name>
>> ---
>>   drivers/net/wireless/mediatek/mt76/mt7915/init.c | 1 -
>>   1 file changed, 1 deletion(-)
>>
>> diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
>> index ee976657bfc3..78552f10b377 100644
>> --- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
>> +++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
>> @@ -414,7 +414,6 @@ mt7915_init_wiphy(struct mt7915_phy *phy)
>>   			if (!dev->dbdc_support)
>>   				vht_cap->cap |=
>>   					IEEE80211_VHT_CAP_SHORT_GI_160 |
>> -					IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ |
>>   					FIELD_PREP(IEEE80211_VHT_CAP_EXT_NSS_BW_MASK, 1);
>>   		} else {
>>   			vht_cap->cap |=
>>
> 
> For some reason this got backported into the stable kernel:
> 
> ```
> $ git log --oneline v6.5.2..v6.5.4 -- drivers/net/wireless/mediatek/mt76/mt7915/
> c43017fbebcc3 wifi: mt76: mt7915: fix power-limits while chan_switch
> edb1afe042c74 wifi: mt76: mt7915: fix tlv length of mt7915_mcu_get_chan_mib_info
> 9ec0dec0baea3 wifi: mt76: mt7915: remove VHT160 capability on MT7915
> 0e61f73e6ebc0 wifi: mt76: mt7915: fix capabilities in non-AP mode
> 6bce28ce28390 wifi: mt76: mt7915: fix command timeout in AP stop period
> 7af917d4864c6 wifi: mt76: mt7915: rework tx bytes counting when WED is active
> feae00c6468ce wifi: mt76: mt7915: rework tx packets counting when WED is active
> 70bbcc4ad6544 wifi: mt76: mt7915: fix background radar event being blocked
> ```
> 
> and this broke my mt7915-based AP.
> 
> However, if I remove `[VT160]` capability from the hostapd config, things go back to normal. It does seem that 160 MHz still works even.
> 
> Is this expected?

I would say it is expected.

hostapd seems to solely rely on the VHT Supported Channel Width and does not 
seem to support the VHT Extended NSS BW stuff.  So it only knows about full VHT 
160 MHz support and not about half NSS VHT 160 MHz.

The hardware does not actually support full 160 MHz (despite the driver 
erroneously claiming support for it before this patch) so it make sense that 
hostapd fails to start the AP if the config file requests (full) VHT 160 MHz.

However, hostapd knows about half NSS HE 160 MHz and I suspect your 
configuration also requests HE 160 MHz, so 160 MHz works fine in HE but not in VHT.

In any case, it would help to know the hostapd version and your configuration file.
Oleksandr Natalenko Sept. 29, 2023, 8:36 p.m. UTC | #7
Hello.

On pátek 29. září 2023 14:59:26 CEST Nicolas Cavallari wrote:
> On 21/09/2023 07:02, Oleksandr Natalenko wrote:
> > Hello Felix.
> > 
> > On středa 26. července 2023 11:17:02 CEST Felix Fietkau wrote:
> >> The IEEE80211_VHT_CAP_EXT_NSS_BW value already indicates support for half-NSS
> >> 160 MHz support, so it is wrong to also advertise full 160 MHz support.
> >>
> >> Fixes: c2f73eacee3b ("wifi: mt76: mt7915: add back 160MHz channel width support for MT7915")
> >> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> >> ---
> >>   drivers/net/wireless/mediatek/mt76/mt7915/init.c | 1 -
> >>   1 file changed, 1 deletion(-)
> >>
> >> diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> >> index ee976657bfc3..78552f10b377 100644
> >> --- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> >> +++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> >> @@ -414,7 +414,6 @@ mt7915_init_wiphy(struct mt7915_phy *phy)
> >>   			if (!dev->dbdc_support)
> >>   				vht_cap->cap |=
> >>   					IEEE80211_VHT_CAP_SHORT_GI_160 |
> >> -					IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ |
> >>   					FIELD_PREP(IEEE80211_VHT_CAP_EXT_NSS_BW_MASK, 1);
> >>   		} else {
> >>   			vht_cap->cap |=
> >>
> > 
> > For some reason this got backported into the stable kernel:
> > 
> > ```
> > $ git log --oneline v6.5.2..v6.5.4 -- drivers/net/wireless/mediatek/mt76/mt7915/
> > c43017fbebcc3 wifi: mt76: mt7915: fix power-limits while chan_switch
> > edb1afe042c74 wifi: mt76: mt7915: fix tlv length of mt7915_mcu_get_chan_mib_info
> > 9ec0dec0baea3 wifi: mt76: mt7915: remove VHT160 capability on MT7915
> > 0e61f73e6ebc0 wifi: mt76: mt7915: fix capabilities in non-AP mode
> > 6bce28ce28390 wifi: mt76: mt7915: fix command timeout in AP stop period
> > 7af917d4864c6 wifi: mt76: mt7915: rework tx bytes counting when WED is active
> > feae00c6468ce wifi: mt76: mt7915: rework tx packets counting when WED is active
> > 70bbcc4ad6544 wifi: mt76: mt7915: fix background radar event being blocked
> > ```
> > 
> > and this broke my mt7915-based AP.
> > 
> > However, if I remove `[VT160]` capability from the hostapd config, things go back to normal. It does seem that 160 MHz still works even.
> > 
> > Is this expected?
> 
> I would say it is expected.
> 
> hostapd seems to solely rely on the VHT Supported Channel Width and does not 
> seem to support the VHT Extended NSS BW stuff.  So it only knows about full VHT 
> 160 MHz support and not about half NSS VHT 160 MHz.
> 
> The hardware does not actually support full 160 MHz (despite the driver 
> erroneously claiming support for it before this patch) so it make sense that 
> hostapd fails to start the AP if the config file requests (full) VHT 160 MHz.
> 
> However, hostapd knows about half NSS HE 160 MHz and I suspect your 
> configuration also requests HE 160 MHz, so 160 MHz works fine in HE but not in VHT.

I see, thanks for the explanation.

> In any case, it would help to know the hostapd version and your configuration file.

It's 2.10 with the following config at the very moment:

```
interface=wlp1s0
ctrl_interface=/run/hostapd/wlp1s0
driver=nl80211
ssid=xxx
utf8_ssid=1
interworking=1
ipaddr_type_availability=12
country_code=XX
auth_algs=1
wpa=2
wpa_key_mgmt=WPA-PSK FT-PSK
wpa_pairwise=CCMP
rsn_pairwise=CCMP
wpa_psk_file=/run/credentials/hostapd@wlp1s0.service/hostapd.wpa_psk
macaddr_acl=1
accept_mac_file=/etc/hostapd/hostapd.accept
noscan=1
hw_mode=a
ieee80211n=1
channel=100
vht_oper_chwidth=2
vht_oper_centr_freq_seg0_idx=114
ieee80211ax=1
he_oper_chwidth=2
he_oper_centr_freq_seg0_idx=114
ieee80211w=1
ocv=1
ieee80211d=1
ieee80211h=1
wmm_enabled=1
ht_capab=[RXLDPC][HT40+][GF][SHORT-GI-20][SHORT-GI-40][TX-STBC][RX-STBC1][MAX-AMSDU-7935][DSSS_CCK-40]
mobility_domain=abcd
ft_psk_generate_local=1
pmk_r1_push=1
rsn_preauth=1
rsn_preauth_interfaces=wifi-br
nas_identifier=yyy
r1_key_holder=yyy
r0kh=ff:ff:ff:ff:ff:ff * zzz
r1kh=00:00:00:00:00:00 00:00:00:00:00:00 zzz
disassoc_low_ack=1
fst_group_id=wifi-br
fst_priority=100
mbo=1
mbo_cell_data_conn_pref=1
require_ht=1
ieee80211ac=1
require_vht=1
vht_capab=[MAX-MPDU-7991][RXLDPC][SHORT-GI-80][SHORT-GI-160][TX-STBC-2BY1][RX-STBC-1][SU-BEAMFORMER][SU-BEAMFORMEE][MU-BEAMFORMER][MU-BEAMFORMEE][RX-ANTENNA-PATTERN][TX-ANTENNA-PATTERN][MAX-A-MPDU-LEN-EXP7]
```

(I wonder if I did other obviously stupid things here)
Linux regression tracking (Thorsten Leemhuis) Oct. 13, 2023, 1:21 p.m. UTC | #8
[TLDR: This mail in primarily relevant for Linux kernel regression
tracking. See link in footer if these mails annoy you.]

On 22.09.23 13:22, Linux regression tracking #adding (Thorsten Leemhuis)
wrote:
> 
> On 21.09.23 07:02, Oleksandr Natalenko wrote:
>> On středa 26. července 2023 11:17:02 CEST Felix Fietkau wrote:
>>> The IEEE80211_VHT_CAP_EXT_NSS_BW value already indicates support for half-NSS
>>> 160 MHz support, so it is wrong to also advertise full 160 MHz support.
> [...]
>> and this broke my mt7915-based AP.
>>
>> However, if I remove `[VT160]` capability from the hostapd config, things go back to normal. It does seem that 160 MHz still works even.
>>
>> Is this expected?
> 
> Thanks for the report.

Removing this from the regression tracking after mentioning the intent
to do so due to the tricky striation in my last report to Linus.

#regzbot inconclusive: tricky situation, no simple way out afaics
#regzbot ignore-activity

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
That page also explains what to do if mails like this annoy you.
diff mbox series

Patch

diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
index ee976657bfc3..78552f10b377 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
@@ -414,7 +414,6 @@  mt7915_init_wiphy(struct mt7915_phy *phy)
 			if (!dev->dbdc_support)
 				vht_cap->cap |=
 					IEEE80211_VHT_CAP_SHORT_GI_160 |
-					IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ |
 					FIELD_PREP(IEEE80211_VHT_CAP_EXT_NSS_BW_MASK, 1);
 		} else {
 			vht_cap->cap |=