On 7/21/2017 11:19 PM, Rafal wrote:
On Fri, 21 Jul 2017, Dan Williams wrote:
On Fri, 2017-07-21 at 16:56 +0200, Rafal wrote:
I have a board with ap6212 chip and I have encountered two problems
with the brcmfmac driver operating with this device. First problem I
describe below, second one in separate mail.
Namely, I have noticed quite poor connection with the device despite
good signal strength. Ping to the device was very uneven, about 50 -
100 ms in average, 10 - 20% of packets loss. After some
investigations I have found that problem is caused by powersave
feature on wiphy (BRCMF_C_SET_PM command). When the value is set to
PM_OFF, the problem does not appear - ping is quite stable, ~2ms.
When set to PM_FAST, the ping is bad.
The brcmfmac driver currently does not have possibility to turn off
the powersave feature. I have added the possibility on 4.11.6 kernel
I don't think that's true? The driver implements the nl80211
set_power_mgmt hook, which lets you turn off powersave with 'iw'. That
seems like a much better option than a module parameter. I know other
drivers have the module parameter, but I personally consider that
legacy/holdover, given that we have runtime toggles for this kind of
thing.
brcmf_cfg80211_set_power_mgmt() should do what you need, right?
Yes, it does.
In fact, I needed only a parameter in OF database. This is a bug in the
device or firmware and I needed to disable the feature for this chip.
Many device drivers allow to specify in OF database that driver should
use a quirk. This is similar situation.
I have added the kernel parameter as an additional feature. I thought
that not all platforms are using devicetree database. But maybe it is a
bad idea.
I was going to make the same remark as Dan. Anyway, the ping times are
not really unexpected. It depends on your beacon period and dtim
setting. However, the packet loss is not expected and will require
analyzing a sniff capture.
Regards,
Arend
