On Tue, Nov 13, 2018 at 9:15 PM Chen-Yu Tsai <wens@xxxxxxxx> wrote: > > On Tue, Nov 13, 2018 at 7:37 AM Rob Herring <robh@xxxxxxxxxx> wrote: > > > > On Wed, Nov 07, 2018 at 06:12:54PM +0800, Chen-Yu Tsai wrote: > > > The Broadcom Bluetooth controllers can take up to two external clocks: > > > an external frequency reference, substituting the main crystal, and a > > > LPO clock at 32.768 kHz substituting the internal LPO clock. > > > > > > In particular, the external LPO clock must be used when the controller > > > does not have NVRAM connected, and the main reference frequency is not > > > the default 20 MHz. This is described in detail in the datasheet. > > > > > > The original "extclk" clock name is ambiguous as to which of these it > > > refers to, and some designs might even require both. > > > > > > This patch deprecates the existing name, and adds "txco" and "lpo". > > > > > > Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx> > > > --- > > > Documentation/devicetree/bindings/net/broadcom-bluetooth.txt | 5 ++++- > > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > > > diff --git a/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt b/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt > > > index 4194ff7e6ee6..2535e54219af 100644 > > > --- a/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt > > > +++ b/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt > > > @@ -18,7 +18,10 @@ Optional properties: > > > - shutdown-gpios: GPIO specifier, used to enable the BT module > > > - device-wakeup-gpios: GPIO specifier, used to wakeup the controller > > > - host-wakeup-gpios: GPIO specifier, used to wakeup the host processor > > > - - clocks: clock specifier if external clock provided to the controller > > > + - clocks and clock-names: clock specifier if external clocks are provided > > > + - "txco": external reference clock > > > + - "extclk": deprecated, replaced by "txco" > > > + - "lpo": external low power 32.768 kHz clock > > > - clock-names: should be "extclk" > > > > This line should change? > > Yes. Missed that. > > > > > 'clocks' needs to describe how many clocks and the order of them. > > > > 'clock-names' needs to list the names. Keep them separate. > > I was under the impression that when clock-names was used, the > order of clocks shouldn't matter. Generally, no. The order should be defined still. > Also, both clocks are optional. The controller can use a standalone > crystal instead of an external TXCO, which would not get described in > the device tree, and/or not use an LPO clock. How would one describe > a device that has an LPO clock input but not a TXCO clock input? A crystal would still be a fixed-clock. Does s/w need to know which one it is? Your's is a case where index alone doesn't work and you need clock-names. But still, you should define the order for when both clocks are present so we don't end with both orders for no good reason. > Last, IMHO listing them with name + description, one item per line > is more readable then having the items on one line, then having the > next line list all their respective names. If ordering and number of > items is important, I could add the requirements to the description > of "clocks and clock-names"? clocks can just say something like "1 or 2 clocks as defined in clock-names". Rob
