On 5 January 2017 at 10:31, Arend Van Spriel
<arend.vanspriel@xxxxxxxxxxxx> wrote:
> On 4-1-2017 22:19, Rafał Miłecki wrote:
>> On 4 January 2017 at 21:07, Arend Van Spriel
>> <arend.vanspriel@xxxxxxxxxxxx> wrote:
>>> On 4-1-2017 18:58, Rafał Miłecki wrote:
>>>> From: Rafał Miłecki <rafal@xxxxxxxxxx>
>>>>
>>>> There are some devices (e.g. Netgear R8000 home router) with one chipset
>>>> model used for different radios, some of them limited to subbands. NVRAM
>>>> entries don't contain any extra info on such limitations and firmware
>>>> reports full list of channels to us. We need to store extra limitation
>>>> info in DT to support such devices properly.
>>>>
>>>> Now there is a cfg80211 helper for reading such info use it in brcmfmac.
>>>> This patch adds check for channel being disabled with orig_flags which
>>>> is how this wiphy helper and wiphy_register work.
>>>>
>>>> Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx>
>>>> ---
>>>> This patch should probably go through wireless-driver-next which is why
>>>> it got weird number 4/3. I'm sending it just as a proof of concept.
>>>> It was succesfully tested on SmartRG SR400ac with BCM43602.
>>>>
>>>> V4: Respect IEEE80211_CHAN_DISABLED in orig_flags
>>>> V5: Update commit message
>>>> V6: Call wiphy_read_of_freq_limits after brcmf_setup_wiphybands to make it work
>>>> with helper setting "flags" instead of "orig_flags".
>>>> ---
>>>> drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 9 ++++++++-
>>>> 1 file changed, 8 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
>>>> index ccae3bb..a008ba5 100644
>>>> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
>>>> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
>>>> @@ -5886,6 +5886,9 @@ static int brcmf_construct_chaninfo(struct brcmf_cfg80211_info *cfg,
>>>> band->band);
>>>> channel[index].hw_value = ch.control_ch_num;
>>>>
>>>> + if (channel->orig_flags & IEEE80211_CHAN_DISABLED)
>>>> + continue;
>>>> +
>>>
>>> So to be clear this is still needed for subsequent calls to
>>> brcmf_setup_wiphybands(). The subsequent calls are done from the
>>> regulatory notifier. So I think we have an issue with this approach. Say
>>> the device comes up with US. That would set DISABLED flags for channels
>>> 12 to 14. With a country update to PL we would want to enable channels
>>> 12 and 13, right? The orig_flags are copied from the initial flags
>>> during wiphy_register() so it seems we will skip enabling 12 and 13. I
>>> think we should remove the check above and call
>>> wiphy_read_of_freq_limits() as a last step within
>>> brcmf_setup_wiphybands(). It means it is called every time, but it
>>> safeguards that the limits in DT are always applied.
>>
>> I'm not exactly happy with channels management in brcmfmac. Before
>> calling wiphy_register it already disables channels unavailable for
>> current country. This results in setting IEEE80211_CHAN_DISABLED in
>
> What do you mean by current country. There is none that we are aware off
> in the driver. So we obtain the channels for the current
> country/revision in the firmware and enable those before
> wiphy_register(). This all is within the probe/init sequence so I do not
> really see an issue. As the wiphy object is not yet registered there is
> no user-space awareness
It seems I'm terrible as describing my patches/problems/ideas :( Here
I used 1 inaccurate word and you couldn't understand my point.
By "current country" I meant current region (and so a set of
regulatory rules) used by the firmware. I believe firmware describes
it using "ccode" and "regrev".
Now, about the issue I see:
AFAIU if you set IEEE80211_CHAN_DISABLED in "orig_flags" it's meant to
be there for good. Some reference code that makes me believe so
(reg.c):
pr_debug("Disabling freq %d MHz for good\n", chan->center_freq);
chan->orig_flags |= IEEE80211_CHAN_DISABLED;
This is what happens with brcmfmac right now. If firmware doesn't
report some channels, you set "flags" to IEEE80211_CHAN_DISABLED for
them. Then you call wiphy_register which copies that "flags" to the
"orig_flags". I read it as: we are never going to use these channels.
Now, consider you support regdom change (I do with my local patches).
You translate alpha2 to a proper firmware request (board specific!),
you execute it and then firmware may allow you to use channels that
you marked as disabled for good. You would need to mess with
orig_flags to recover from this issue.
Does my explanation make more sense of this issue now?
>> orig_flags of channels that may become available later, after country
>> change. Please note it happens even right now, without this patch.
>
> Nope. As stated earlier the country setting in firmware is not updated
> unless you provide a *proper* mapping of user-space country code to
> firmware country code/revision. That is the reason, ie. firmware simply
> returns the same list of channels as nothing changed from its
> perspective. We may actually drop 11d support.
I implemented mapping support locally, this is the feature I'm talking about.
>> Maybe you can workaround this by ignoring orig_flags in custom
>> regulatory code, but I'd just prefer to have it nicely handled in the
>> first place.
>
> Please care to explain your ideas before putting any effort in this
> "feature". As the author of the code that makes you unhappy and as
> driver maintainer I would like to get a clearer picture of your point of
> view. What exactly is the issue that makes you unhappy.
I meant that problem with "orig_flags" I described in the first
paragraph. I wasn't trying to hide whatever issue I'm seeing, I swear
;)
>> This is the next feature I'm going to work on. AFAIU this patch won't
>> be applied for now (it's for wireless-drivers-next and we first need
>> to get wiphy_read_of_freq_limits in that tree). By the time that
>> happens I may have another patchset cleaning brcmfmac ready. And FWIW
>> this patch wouldn't make things worse *at this point* as we don't
>> really support country switching for any device yet.
>
> Now who is *we*? We as Broadcom can, because we know how to map the ISO
> 3166-1 country code to firmware country code/revision for a specific
> firmware release. Firmware uses its own regulatory rules which may
> differ from what regdb has. Now I know Intel submitted a mechanism to
> export firmware rules to regdb so maybe we should consider switching to
> that api if that has been upstreamed. Need to check.
We as a driver developers. Please read
"we don't really support country switching for any device yet"
as
"brcmfmac doesn't really support country switching for any device yet"
Does it help to get the context?
--
Rafał
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
