On Mon, Oct 3, 2016 at 5:22 PM, Rob Herring <robh+dt@xxxxxxxxxx> wrote: > On Sun, Oct 2, 2016 at 5:50 PM, Martin Blumenstingl > <martin.blumenstingl@xxxxxxxxxxxxxx> wrote: >> There are at least two drivers (ath9k and mt76) out there, where >> devicetree authors need to override the enabled bands. >> >> For ath9k there is only one use-case: disabling a band which has been >> incorrectly enabled by the vendor in the EEPROM (enabling a band is not >> possible because the calibration data would be missing in the EEPROM). >> The mt76 driver (currently pending for review) however allows enabling >> and disabling the 2.4GHz and 5GHz band, see [0]. >> >> Based on the discussion of (earlier versions of) my ath9k devicetree >> patch it was suggested [1] that we use enable- and disable- properties. >> The current patch implements: >> - bands can be enabled or disabled with the corresponding property >> - if both (disable and enable) properties are given and a driver asks >> whether the band is enabled then the logic will return false (= not >> enabled, preferring the disabled flag) >> - if both (disable and enable) properties are given and a driver asks >> whether the band is disabled then the logic will return true (again, >> preferring the disabled flag over the enabled flag) >> >> We can still change the logic to do what the mt76 driver does (I am >> fine with both solutions): >> - property not available: driver decides which bands to enable >> - property set to 0: disable the band >> - property set to 1: enable the band > > I prefer this way. Really, I'd prefer just a boolean disable property. > I'm not sure why you need the enable. We usually have these tri-state > properties when you want not present to mean use the bootloader or > default setting. Try to make not present the most common case. Felix: could you please give a few details why mt76 can not only disable but also enable a specific band? There is no specific comment in the sources [0] why this is needed. All other drivers that I am aware of (ath9k, rt2x00) only allow disabling a specific band, they never enable it (this has to be done explicitly by the EEPROM). >> The new code has been integrated into ath9k to demonstrate how to use >> it (with the benefit that the disable_2ghz and disable_5ghz settings >> from the ath9k_platform_data can now also be configured via .dts). >> >> open questions/decisions needed: >> - where to place this new code? I put it into drivers/of/of_ieee80211 >> because that's where most other functions live. >> However, I found that this makes backporting the code harder (using >> wireless-backports from the driver-backports project [2]) > > We are generally moving subsystem specific code like this out of > drivers/of/, so please do that here. Maybe someone will get motivated > to move the other networking code out too. OK, thanks for the hint. [0] https://github.com/openwrt/mt76/blob/master/eeprom.c
