[PATCH] Documentation: dt: bindings: TI WiLink modules

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Luciano Coelho]

(oh crap, now *really* fixed the ARM mailing list address)

On Tue, 2013-06-25 at 11:35 +0300, Luciano Coelho wrote:
> Add device tree bindings documentation for the TI WiLink modules.
> Currently only the WLAN part of the WiLink6, WiLink7 and WiLink8
> modules is supported.
> 
> Signed-off-by: Luciano Coelho <coelho@ti.com>
> ---
> 
> I created a new directory under net to contain wireless bindings documentation.
> 
> The actual implementation in the driver will follow separately.
> 
>  .../devicetree/bindings/net/wireless/ti-wilink.txt |   46 ++++++++++++++++++++
>  1 file changed, 46 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/net/wireless/ti-wilink.txt
> 
> diff --git a/Documentation/devicetree/bindings/net/wireless/ti-wilink.txt b/Documentation/devicetree/bindings/net/wireless/ti-wilink.txt
> new file mode 100644
> index 0000000..d8e8bfbb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/wireless/ti-wilink.txt
> @@ -0,0 +1,46 @@
> +TI WiLink Wireless Modules Device Tree Bindings
> +===============================================
> +
> +The WiLink modules provide wireless connectivity, such as WLAN,
> +Bluetooth, FM and NFC.
> +
> +There are several different modules available, which can be grouped by
> +their generation: WiLink6, WiLink7 and WiLink8.  WiLink4 is not
> +currently supported with device tree.
> +
> +Currently, only the WLAN portion of the modules is supported with
> +device tree.
> +
> +Required properties:
> +--------------------
> +
> +- compatible: should be "ti,wilink6", "ti,wilink7" or "ti,wilink8"
> +- interrupt-parent: the interrupt controller
> +- interrupts: out-of-band WLAN interrupt
> +	See the interrupt controller's bindings documentation for
> +	detailed definition.
> +
> +Optional properties:
> +--------------------
> +
> +- refclock: the internal WLAN reference clock frequency (required for
> +  WiLink6 and WiLink7; not used for WiLink8).  Must be one of the
> +  following:
> +	0 = 19.2 MHz
> +	1 = 26.0 MHz
> +	2 = 38.4 MHz
> +	3 = 52.0 MHz
> +	4 = 38.4 MHz, XTAL
> +	5 = 26.0 MHz, XTAL
> +
> +- tcxoclock: the internal WLAN TCXO clock frequency (required for
> +  WiLink7 not used for WiLink6 and WiLink8).  Must be one of the
> +  following:
> +	0 = 19.200 MHz
> +	1 = 26.000 MHz
> +	2 = 38.400 MHz
> +	3 = 52.000 MHz
> +	4 = 16.368 MHz
> +	5 = 32.736 MHz
> +	6 = 16.800 MHz
> +	7 = 33.600 MHz

If this is okay for everyone, can I push this via my tree (which goes to
linux-wireless->net->linus)? I think it makes more sense to send the
documentation together with the patch that actually implements the DT
node parsing in the driver.

--
Luca.

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Tony Lindgren]

* Luciano Coelho <coelho@ti.com> [130625 12:43]:
> (oh crap, now *really* fixed the ARM mailing list address)
> 
> On Tue, 2013-06-25 at 11:35 +0300, Luciano Coelho wrote:
> > Add device tree bindings documentation for the TI WiLink modules.
> > Currently only the WLAN part of the WiLink6, WiLink7 and WiLink8
> > modules is supported.
> > 
> > Signed-off-by: Luciano Coelho <coelho@ti.com>
> > ---
> > 
> > I created a new directory under net to contain wireless bindings documentation.
> > 
> > The actual implementation in the driver will follow separately.
> > 
> >  .../devicetree/bindings/net/wireless/ti-wilink.txt |   46 ++++++++++++++++++++
> >  1 file changed, 46 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/net/wireless/ti-wilink.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/net/wireless/ti-wilink.txt b/Documentation/devicetree/bindings/net/wireless/ti-wilink.txt
> > new file mode 100644
> > index 0000000..d8e8bfbb
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/net/wireless/ti-wilink.txt
> > @@ -0,0 +1,46 @@
> > +TI WiLink Wireless Modules Device Tree Bindings
> > +===============================================
> > +
> > +The WiLink modules provide wireless connectivity, such as WLAN,
> > +Bluetooth, FM and NFC.
> > +
> > +There are several different modules available, which can be grouped by
> > +their generation: WiLink6, WiLink7 and WiLink8.  WiLink4 is not
> > +currently supported with device tree.
> > +
> > +Currently, only the WLAN portion of the modules is supported with
> > +device tree.
> > +
> > +Required properties:
> > +--------------------
> > +
> > +- compatible: should be "ti,wilink6", "ti,wilink7" or "ti,wilink8"
> > +- interrupt-parent: the interrupt controller
> > +- interrupts: out-of-band WLAN interrupt
> > +	See the interrupt controller's bindings documentation for
> > +	detailed definition.
> > +
> > +Optional properties:
> > +--------------------
> > +
> > +- refclock: the internal WLAN reference clock frequency (required for
> > +  WiLink6 and WiLink7; not used for WiLink8).  Must be one of the
> > +  following:
> > +	0 = 19.2 MHz
> > +	1 = 26.0 MHz
> > +	2 = 38.4 MHz
> > +	3 = 52.0 MHz
> > +	4 = 38.4 MHz, XTAL
> > +	5 = 26.0 MHz, XTAL

This is just the omap refclock, right? If so, you can just pass the
standard clock phandle. I know we don't yet have the DT clocks merged,
but Tero just posted another revision of those.

> > +- tcxoclock: the internal WLAN TCXO clock frequency (required for
> > +  WiLink7 not used for WiLink6 and WiLink8).  Must be one of the
> > +  following:
> > +	0 = 19.200 MHz
> > +	1 = 26.000 MHz
> > +	2 = 38.400 MHz
> > +	3 = 52.000 MHz
> > +	4 = 16.368 MHz
> > +	5 = 32.736 MHz
> > +	6 = 16.800 MHz
> > +	7 = 33.600 MHz

Where does this clock come from? Maybe this can be set based on the
compatible value if it's completely internal?
 
> If this is okay for everyone, can I push this via my tree (which goes to
> linux-wireless->net->linus)? I think it makes more sense to send the
> documentation together with the patch that actually implements the DT
> node parsing in the driver.

If we can use the standard bindings, it might be worth waiting until
we have the DT clocks available as we have the pdata workaround merged
anyways. That's because then we don't need to support the custom
binding later on ;)

Regards,

Tony

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Luciano Coelho]

Hi Tony,

On Tue, 2013-06-25 at 23:24 -0700, Tony Lindgren wrote:
> * Luciano Coelho <coelho@ti.com> [130625 12:43]:
> > On Tue, 2013-06-25 at 11:35 +0300, Luciano Coelho wrote:
> > > Add device tree bindings documentation for the TI WiLink modules.
> > > Currently only the WLAN part of the WiLink6, WiLink7 and WiLink8
> > > modules is supported.
> > > 
> > > Signed-off-by: Luciano Coelho <coelho@ti.com>
> > > ---

[...]

> > > +Optional properties:
> > > +--------------------
> > > +
> > > +- refclock: the internal WLAN reference clock frequency (required for
> > > +  WiLink6 and WiLink7; not used for WiLink8).  Must be one of the
> > > +  following:
> > > +	0 = 19.2 MHz
> > > +	1 = 26.0 MHz
> > > +	2 = 38.4 MHz
> > > +	3 = 52.0 MHz
> > > +	4 = 38.4 MHz, XTAL
> > > +	5 = 26.0 MHz, XTAL
> 
> This is just the omap refclock, right? If so, you can just pass the
> standard clock phandle. I know we don't yet have the DT clocks merged,
> but Tero just posted another revision of those.

This is an internal clock.  This clock is part of the module that
contains the WiLink chip.  It is not associated with the clocks in the
main board (OMAP).


> > > +- tcxoclock: the internal WLAN TCXO clock frequency (required for
> > > +  WiLink7 not used for WiLink6 and WiLink8).  Must be one of the
> > > +  following:
> > > +	0 = 19.200 MHz
> > > +	1 = 26.000 MHz
> > > +	2 = 38.400 MHz
> > > +	3 = 52.000 MHz
> > > +	4 = 16.368 MHz
> > > +	5 = 32.736 MHz
> > > +	6 = 16.800 MHz
> > > +	7 = 33.600 MHz
> 
> Where does this clock come from? Maybe this can be set based on the
> compatible value if it's completely internal?

This is also a completely internal clock.  My "compatible" values are
based on the WiLink chip itself, not in the module that contains the
chip.  There are several modules and they are the ones that specify the
clock frequencies.  This data I'm passing here is just to tell the
WiLink chip which frequencies the module uses.

My driver is for the WiLink chip itself, not to the module (in theory).
So I think having the WiLink values as bindings would be more generic
than having to specify values for each available module (eg.
"lsr-research,tiwi-ble") and mapping those values to specific
frequencies in the driver.

 
> > If this is okay for everyone, can I push this via my tree (which goes to
> > linux-wireless->net->linus)? I think it makes more sense to send the
> > documentation together with the patch that actually implements the DT
> > node parsing in the driver.
> 
> If we can use the standard bindings, it might be worth waiting until
> we have the DT clocks available as we have the pdata workaround merged
> anyways. That's because then we don't need to support the custom
> binding later on ;)

I looked into Tero's patches and I considered using the generic clock
bindings, but I think it doesn't make sense in this case.  The thing is
that the module is not providing the clocks to the main board.  Neither
is the WiLink chip consuming clocks from the main board.

I thought about specifying clock providers and consumers to be used only
by the module and WiLink chip, but I think it's overkill.  And we would
also have to find a way to prevent the main clock framework from trying
to handle them.

So, my conclusion was that, even though these *are* clocks, from the
main board's perspective they're just specifications of what the module
looks like.

Does this make sense?

--
Cheers,
Luca.

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Tony Lindgren]

* Luciano Coelho <coelho@ti.com> [130626 01:19]:
> Hi Tony,
> 
> On Tue, 2013-06-25 at 23:24 -0700, Tony Lindgren wrote:
> > * Luciano Coelho <coelho@ti.com> [130625 12:43]:
> > > On Tue, 2013-06-25 at 11:35 +0300, Luciano Coelho wrote:
> > > > Add device tree bindings documentation for the TI WiLink modules.
> > > > Currently only the WLAN part of the WiLink6, WiLink7 and WiLink8
> > > > modules is supported.
> > > > 
> > > > Signed-off-by: Luciano Coelho <coelho@ti.com>
> > > > ---
> 
> [...]
> 
> > > > +Optional properties:
> > > > +--------------------
> > > > +
> > > > +- refclock: the internal WLAN reference clock frequency (required for
> > > > +  WiLink6 and WiLink7; not used for WiLink8).  Must be one of the
> > > > +  following:
> > > > +	0 = 19.2 MHz
> > > > +	1 = 26.0 MHz
> > > > +	2 = 38.4 MHz
> > > > +	3 = 52.0 MHz
> > > > +	4 = 38.4 MHz, XTAL
> > > > +	5 = 26.0 MHz, XTAL
> > 
> > This is just the omap refclock, right? If so, you can just pass the
> > standard clock phandle. I know we don't yet have the DT clocks merged,
> > but Tero just posted another revision of those.
> 
> This is an internal clock.  This clock is part of the module that
> contains the WiLink chip.  It is not associated with the clocks in the
> main board (OMAP).
> 
> 
> > > > +- tcxoclock: the internal WLAN TCXO clock frequency (required for
> > > > +  WiLink7 not used for WiLink6 and WiLink8).  Must be one of the
> > > > +  following:
> > > > +	0 = 19.200 MHz
> > > > +	1 = 26.000 MHz
> > > > +	2 = 38.400 MHz
> > > > +	3 = 52.000 MHz
> > > > +	4 = 16.368 MHz
> > > > +	5 = 32.736 MHz
> > > > +	6 = 16.800 MHz
> > > > +	7 = 33.600 MHz
> > 
> > Where does this clock come from? Maybe this can be set based on the
> > compatible value if it's completely internal?
> 
> This is also a completely internal clock.  My "compatible" values are
> based on the WiLink chip itself, not in the module that contains the
> chip.  There are several modules and they are the ones that specify the
> clock frequencies.  This data I'm passing here is just to tell the
> WiLink chip which frequencies the module uses.
> 
> My driver is for the WiLink chip itself, not to the module (in theory).
> So I think having the WiLink values as bindings would be more generic
> than having to specify values for each available module (eg.
> "lsr-research,tiwi-ble") and mapping those values to specific
> frequencies in the driver.
> 
>  
> > > If this is okay for everyone, can I push this via my tree (which goes to
> > > linux-wireless->net->linus)? I think it makes more sense to send the
> > > documentation together with the patch that actually implements the DT
> > > node parsing in the driver.
> > 
> > If we can use the standard bindings, it might be worth waiting until
> > we have the DT clocks available as we have the pdata workaround merged
> > anyways. That's because then we don't need to support the custom
> > binding later on ;)
> 
> I looked into Tero's patches and I considered using the generic clock
> bindings, but I think it doesn't make sense in this case.  The thing is
> that the module is not providing the clocks to the main board.  Neither
> is the WiLink chip consuming clocks from the main board.
> 
> I thought about specifying clock providers and consumers to be used only
> by the module and WiLink chip, but I think it's overkill.  And we would
> also have to find a way to prevent the main clock framework from trying
> to handle them.
> 
> So, my conclusion was that, even though these *are* clocks, from the
> main board's perspective they're just specifications of what the module
> looks like.
> 
> Does this make sense?

OK yes, in that case looks fine to me:

Acked-by: Tony Lindgren <tony@atomide.com>

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Nishanth Menon]

On Thu, Jun 27, 2013 at 8:30 AM, Luciano Coelho <coelho@ti.com> wrote:
> On Thu, 2013-06-27 at 08:23 -0500, Nishanth Menon wrote:
>> On 06/27/2013 08:19 AM, Luciano Coelho wrote:
>> > On Thu, 2013-06-27 at 08:15 -0500, Nishanth Menon wrote:
>> >> On Thu, Jun 27, 2013 at 7:58 AM, Luciano Coelho <coelho@ti.com> wrote:
>> >>> For the actual DTS files, I could add a wilink.dtsi with enumerations
>> >>> for these values so they could be used in the node definitions.  But I'm
>> >>> not sure it's going to be that valuable in the end.
>> >> The  way GPIO HIGH was defined might help to provide guidance I think :)
>> >
>> > Where? As far as I can see, the GPIO flags are defined in a bitmap.
>>
>> include/dt-bindings/gpio/gpio.h
>
> Thanks! I don't see these macros used anywhere, though.
umm... I'd think you have'nt looked deep enough / lists :)

>
>> And corresponding kernel header:
>> include/linux/of_gpio.h
>
> This seems to be a completely different thing.  This is the header that
> contains the helper functions to get GPIO-related device tree nodes,
> isn't it?
That is true, but it also contains the flag for level which needs to
be in sync with the gpio.h dts header.
>> just a hint. not saying frequencies were defined in header. for systems
>> that define frequencies - example cpufreq OPPs, clock node usage, we do
>> not use indexing to frequency, instead, that is the responsibility of
>> driver to convert frequency back to required index.
>> git grep frequency Documentation/devicetree/bindings gives you how the
>> precedence looks like.
>>
>> Personally, if given a choice, I'd go with actual frequencies rather
>> than indexes.
>
> If I do that, I need to add also a separate flag to define whether the
> XTAL clock is used or not.  For instance, we have 26MHz and 26MHz
> crystal; and 38.4MHz and 38.4MHz crystal...
Yes, you would have to. at the same time, it is easy for module maker
to provide dtsi corresponding to exact h/w representation on his
module using wilink chip without being worried about weird index value
whose meaning is hidden in binding
On the flip side, It also allows driver to reject frequencies /
configurations that are not supported by the corresponding chip.

As I said, just my 2 cents. Personally, I'd like dts files to be as
readable as c files without having to dig through bindings document.

Regards,
Nishanth Menon

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Luciano Coelho]

On Thu, 2013-06-27 at 08:39 -0500, Nishanth Menon wrote:
> On Thu, Jun 27, 2013 at 8:30 AM, Luciano Coelho <coelho@ti.com> wrote:
> > On Thu, 2013-06-27 at 08:23 -0500, Nishanth Menon wrote:
> >> On 06/27/2013 08:19 AM, Luciano Coelho wrote:
> >> > On Thu, 2013-06-27 at 08:15 -0500, Nishanth Menon wrote:
> >> >> On Thu, Jun 27, 2013 at 7:58 AM, Luciano Coelho <coelho@ti.com> wrote:
> >> >>> For the actual DTS files, I could add a wilink.dtsi with enumerations
> >> >>> for these values so they could be used in the node definitions.  But I'm
> >> >>> not sure it's going to be that valuable in the end.
> >> >> The  way GPIO HIGH was defined might help to provide guidance I think :)
> >> >
> >> > Where? As far as I can see, the GPIO flags are defined in a bitmap.
> >>
> >> include/dt-bindings/gpio/gpio.h
> >
> > Thanks! I don't see these macros used anywhere, though.
> umm... I'd think you have'nt looked deep enough / lists :)

If you mean mailing lists, you're right, I didn't.  I just did a git
grep for the macros and didn't find any users.


> >> And corresponding kernel header:
> >> include/linux/of_gpio.h
> >
> > This seems to be a completely different thing.  This is the header that
> > contains the helper functions to get GPIO-related device tree nodes,
> > isn't it?
> That is true, but it also contains the flag for level which needs to
> be in sync with the gpio.h dts header.
> >> just a hint. not saying frequencies were defined in header. for systems
> >> that define frequencies - example cpufreq OPPs, clock node usage, we do
> >> not use indexing to frequency, instead, that is the responsibility of
> >> driver to convert frequency back to required index.
> >> git grep frequency Documentation/devicetree/bindings gives you how the
> >> precedence looks like.
> >>
> >> Personally, if given a choice, I'd go with actual frequencies rather
> >> than indexes.
> >
> > If I do that, I need to add also a separate flag to define whether the
> > XTAL clock is used or not.  For instance, we have 26MHz and 26MHz
> > crystal; and 38.4MHz and 38.4MHz crystal...
> Yes, you would have to. at the same time, it is easy for module maker
> to provide dtsi corresponding to exact h/w representation on his
> module using wilink chip without being worried about weird index value
> whose meaning is hidden in binding

The module makers need to know about the bindings and read the document
before they specify the node in DTS.  I think for clarity, a comment in
the DTS file stating the actual frequency is good enough.  Simpler and
more efficient (in terms of DT binary size and module code size) than
adding the actual frequencies.


> On the flip side, It also allows driver to reject frequencies /
> configurations that are not supported by the corresponding chip.

It's actually much easier to reject frequencies that are not valid with
the enumeration.  "if (refclock > 5) { bail_out(); }".  If I need to
check every frequency, I need to add an array of valid frequencies and
so on.  Waste of code, IMHO.


> As I said, just my 2 cents. Personally, I'd like dts files to be as
> readable as c files without having to dig through bindings document.

As I said before, for readability, adding a comment with the frequency
is good enough.  This is what I did for PandaES's DTS (not sent out
yet):

	wlan {
	     compatible = "ti,wilink6";
	     interrupt-parent = <&gpio2>;
	     interrupts = <21 0x4>;	/* gpio line 53, high level triggered */
	     refclock = <2>;		/* 38.4 MHz */
	 };

Looks more readable to me than:

	wlan {
	     compatible = "ti,wilink6";
	     interrupt-parent = <&gpio2>;
	     interrupts = <21 0x4>;	/* gpio line 53, high level triggered */
	     refclock = <38400>;
	     refclock_xtal = <0>;
	 };

The macro idea sounds better to me, but in this case this code is so
simple that I don't think it's really worth it.

And, from another point of view, I see this as only a specification of
the module's details.  The frequency value is not really used anywhere
outside the module, so we don't see it.  I don't think there's a good
reason to expose the actual frequency to the kernel (and parse it back
to the values the firmware needs), since nothing else inside the kernel
will care about it.

--
Luca.

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Nishanth Menon]

On 06/27/2013 01:51 PM, Luciano Coelho wrote:
> On Thu, 2013-06-27 at 08:39 -0500, Nishanth Menon wrote:
>> On Thu, Jun 27, 2013 at 8:30 AM, Luciano Coelho <coelho@ti.com> wrote:
>>> On Thu, 2013-06-27 at 08:23 -0500, Nishanth Menon wrote:
>>>> On 06/27/2013 08:19 AM, Luciano Coelho wrote:
>>>>> On Thu, 2013-06-27 at 08:15 -0500, Nishanth Menon wrote:
>>>>>> On Thu, Jun 27, 2013 at 7:58 AM, Luciano Coelho <coelho@ti.com> wrote:
>>>>>>> For the actual DTS files, I could add a wilink.dtsi with enumerations
>>>>>>> for these values so they could be used in the node definitions.  But I'm
>>>>>>> not sure it's going to be that valuable in the end.
>>>>>> The  way GPIO HIGH was defined might help to provide guidance I think :)
>>>>>
>>>>> Where? As far as I can see, the GPIO flags are defined in a bitmap.
>>>>
>>>> include/dt-bindings/gpio/gpio.h
>>>
>>> Thanks! I don't see these macros used anywhere, though.
>> umm... I'd think you have'nt looked deep enough / lists :)
>
> If you mean mailing lists, you're right, I didn't.  I just did a git
> grep for the macros and didn't find any users.
git grep "GPIO_ACTIVE_[HIGH|LOW]" arch/arm/boot/dts/|wc -l
344
on next-20130626. anyways, besides the point.


>>> This seems to be a completely different thing.  This is the header that
>>> contains the helper functions to get GPIO-related device tree nodes,
>>> isn't it?
>> That is true, but it also contains the flag for level which needs to
>> be in sync with the gpio.h dts header.
>>>> just a hint. not saying frequencies were defined in header. for systems
>>>> that define frequencies - example cpufreq OPPs, clock node usage, we do
>>>> not use indexing to frequency, instead, that is the responsibility of
>>>> driver to convert frequency back to required index.
>>>> git grep frequency Documentation/devicetree/bindings gives you how the
>>>> precedence looks like.
>>>>
>>>> Personally, if given a choice, I'd go with actual frequencies rather
>>>> than indexes.
>>>
>>> If I do that, I need to add also a separate flag to define whether the
>>> XTAL clock is used or not.  For instance, we have 26MHz and 26MHz
>>> crystal; and 38.4MHz and 38.4MHz crystal...
>> Yes, you would have to. at the same time, it is easy for module maker
>> to provide dtsi corresponding to exact h/w representation on his
>> module using wilink chip without being worried about weird index value
>> whose meaning is hidden in binding
>
> The module makers need to know about the bindings and read the document
> before they specify the node in DTS.  I think for clarity, a comment in
> the DTS file stating the actual frequency is good enough.  Simpler and
> more efficient (in terms of DT binary size and module code size) than
> adding the actual frequencies.
>
>
>> On the flip side, It also allows driver to reject frequencies /
>> configurations that are not supported by the corresponding chip.
>
> It's actually much easier to reject frequencies that are not valid with
> the enumeration.  "if (refclock > 5) { bail_out(); }".  If I need to
> check every frequency, I need to add an array of valid frequencies and
> so on.  Waste of code, IMHO.
>
>
>> As I said, just my 2 cents. Personally, I'd like dts files to be as
>> readable as c files without having to dig through bindings document.
>
> As I said before, for readability, adding a comment with the frequency
> is good enough.  This is what I did for PandaES's DTS (not sent out
> yet):
>
> 	wlan {
> 	     compatible = "ti,wilink6";
> 	     interrupt-parent = <&gpio2>;
> 	     interrupts = <21 0x4>;	/* gpio line 53, high level triggered */
> 	     refclock = <2>;		/* 38.4 MHz */
> 	 };
>
> Looks more readable to me than:
>
> 	wlan {
> 	     compatible = "ti,wilink6";
> 	     interrupt-parent = <&gpio2>;
> 	     interrupts = <21 0x4>;	/* gpio line 53, high level triggered */
> 	     refclock = <38400>;
> 	     refclock_xtal = <0>;
> 	 };
>
> The macro idea sounds better to me, but in this case this code is so
> simple that I don't think it's really worth it.
>
> And, from another point of view, I see this as only a specification of
> the module's details.  The frequency value is not really used anywhere
> outside the module, so we don't see it.  I don't think there's a good
> reason to expose the actual frequency to the kernel (and parse it back
> to the values the firmware needs), since nothing else inside the kernel
> will care about it.
Overview: we are adding bindings for 
Documentation/devicetree/bindings/net/wireless/ti-wilink.txt Which I 
believe is intended to be generic.

Current frequencies supported for tcxoclock is the following for WiLink7
+	0 = 19.200 MHz
+	1 = 26.000 MHz
+	2 = 38.400 MHz
+	3 = 52.000 MHz
+	4 = 16.368 MHz
+	5 = 32.736 MHz
+	6 = 16.800 MHz
+	7 = 33.600 MHz
Say wilink9 comes along and redefines this map OR introduces support for 
20MHz support making the map 0-8, you'd no longer be able to support 
this map. or say a new update of firmware magically changes this mapping 
or something unexpected.

If the translation and validation is done in the driver, it is trivial 
to handle without redefining the binding and breaking older dtbs (if 
relevant)

Indexes to another entity is always a maintenance burden in the longer 
run and needs judicious control. If it is possible to avoid it by 
selecting the right parameters, I am a hard advocate for the same.

-- 
Regards,
Nishanth Menon

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Luciano Coelho]

On Thu, 2013-06-27 at 14:12 -0500, Nishanth Menon wrote:
> On 06/27/2013 01:51 PM, Luciano Coelho wrote:
> > On Thu, 2013-06-27 at 08:39 -0500, Nishanth Menon wrote:
> >> On Thu, Jun 27, 2013 at 8:30 AM, Luciano Coelho <coelho@ti.com> wrote:
> >>> On Thu, 2013-06-27 at 08:23 -0500, Nishanth Menon wrote:
> >>>> On 06/27/2013 08:19 AM, Luciano Coelho wrote:
> >>>>> On Thu, 2013-06-27 at 08:15 -0500, Nishanth Menon wrote:
> >>>>>> On Thu, Jun 27, 2013 at 7:58 AM, Luciano Coelho <coelho@ti.com> wrote:
> >>>>>>> For the actual DTS files, I could add a wilink.dtsi with enumerations
> >>>>>>> for these values so they could be used in the node definitions.  But I'm
> >>>>>>> not sure it's going to be that valuable in the end.
> >>>>>> The  way GPIO HIGH was defined might help to provide guidance I think :)
> >>>>>
> >>>>> Where? As far as I can see, the GPIO flags are defined in a bitmap.
> >>>>
> >>>> include/dt-bindings/gpio/gpio.h
> >>>
> >>> Thanks! I don't see these macros used anywhere, though.
> >> umm... I'd think you have'nt looked deep enough / lists :)
> >
> > If you mean mailing lists, you're right, I didn't.  I just did a git
> > grep for the macros and didn't find any users.
> git grep "GPIO_ACTIVE_[HIGH|LOW]" arch/arm/boot/dts/|wc -l
> 344
> on next-20130626. anyways, besides the point.
> 
> 
> >>> This seems to be a completely different thing.  This is the header that
> >>> contains the helper functions to get GPIO-related device tree nodes,
> >>> isn't it?
> >> That is true, but it also contains the flag for level which needs to
> >> be in sync with the gpio.h dts header.
> >>>> just a hint. not saying frequencies were defined in header. for systems
> >>>> that define frequencies - example cpufreq OPPs, clock node usage, we do
> >>>> not use indexing to frequency, instead, that is the responsibility of
> >>>> driver to convert frequency back to required index.
> >>>> git grep frequency Documentation/devicetree/bindings gives you how the
> >>>> precedence looks like.
> >>>>
> >>>> Personally, if given a choice, I'd go with actual frequencies rather
> >>>> than indexes.
> >>>
> >>> If I do that, I need to add also a separate flag to define whether the
> >>> XTAL clock is used or not.  For instance, we have 26MHz and 26MHz
> >>> crystal; and 38.4MHz and 38.4MHz crystal...
> >> Yes, you would have to. at the same time, it is easy for module maker
> >> to provide dtsi corresponding to exact h/w representation on his
> >> module using wilink chip without being worried about weird index value
> >> whose meaning is hidden in binding
> >
> > The module makers need to know about the bindings and read the document
> > before they specify the node in DTS.  I think for clarity, a comment in
> > the DTS file stating the actual frequency is good enough.  Simpler and
> > more efficient (in terms of DT binary size and module code size) than
> > adding the actual frequencies.
> >
> >
> >> On the flip side, It also allows driver to reject frequencies /
> >> configurations that are not supported by the corresponding chip.
> >
> > It's actually much easier to reject frequencies that are not valid with
> > the enumeration.  "if (refclock > 5) { bail_out(); }".  If I need to
> > check every frequency, I need to add an array of valid frequencies and
> > so on.  Waste of code, IMHO.
> >
> >
> >> As I said, just my 2 cents. Personally, I'd like dts files to be as
> >> readable as c files without having to dig through bindings document.
> >
> > As I said before, for readability, adding a comment with the frequency
> > is good enough.  This is what I did for PandaES's DTS (not sent out
> > yet):
> >
> > 	wlan {
> > 	     compatible = "ti,wilink6";
> > 	     interrupt-parent = <&gpio2>;
> > 	     interrupts = <21 0x4>;	/* gpio line 53, high level triggered */
> > 	     refclock = <2>;		/* 38.4 MHz */
> > 	 };
> >
> > Looks more readable to me than:
> >
> > 	wlan {
> > 	     compatible = "ti,wilink6";
> > 	     interrupt-parent = <&gpio2>;
> > 	     interrupts = <21 0x4>;	/* gpio line 53, high level triggered */
> > 	     refclock = <38400>;
> > 	     refclock_xtal = <0>;
> > 	 };
> >
> > The macro idea sounds better to me, but in this case this code is so
> > simple that I don't think it's really worth it.
> >
> > And, from another point of view, I see this as only a specification of
> > the module's details.  The frequency value is not really used anywhere
> > outside the module, so we don't see it.  I don't think there's a good
> > reason to expose the actual frequency to the kernel (and parse it back
> > to the values the firmware needs), since nothing else inside the kernel
> > will care about it.
> Overview: we are adding bindings for 
> Documentation/devicetree/bindings/net/wireless/ti-wilink.txt Which I 
> believe is intended to be generic.
> 
> Current frequencies supported for tcxoclock is the following for WiLink7
> +	0 = 19.200 MHz
> +	1 = 26.000 MHz
> +	2 = 38.400 MHz
> +	3 = 52.000 MHz
> +	4 = 16.368 MHz
> +	5 = 32.736 MHz
> +	6 = 16.800 MHz
> +	7 = 33.600 MHz
> Say wilink9 comes along and redefines this map OR introduces support for 
> 20MHz support making the map 0-8, you'd no longer be able to support 
> this map. or say a new update of firmware magically changes this mapping 
> or something unexpected.

No problem with adding 20MHz support.  Look at 6 = 16.800 MHz.  That's
already out of order, so why would 20MHz have to change the mapping?

It is true that stupid changes happen in the firmware from time to time.
But if it happens, the translation could still be done in the driver.

> If the translation and validation is done in the driver, it is trivial 
> to handle without redefining the binding and breaking older dtbs (if 
> relevant)

The validation can still be done in the driver.  I don't think anything
has to break here.  The bindings document is the de-facto specifications
of this stuff.  If something in the lower layers (ie. firmware) breaks,
the driver can do the translation without having to change anything in
the DTS.


> Indexes to another entity is always a maintenance burden in the longer 
> run and needs judicious control. If it is possible to avoid it by 
> selecting the right parameters, I am a hard advocate for the same.

I tend to agree.  But you need a balance.  In theory you're right.  But
I think if you take the real world example, it is over-engineering.

Anyway, if you *really* think this needs to be changed, I think we're in
a deadlock here and I'd like to hear other people's opinions.  I don't
mind making the change, but I'm still not convinced it is worth it,
since it just adds complexity.

And hey, this is too much bikeshedding for such a small detail.

--
Luca.

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Nishanth Menon]

On 06/27/2013 02:46 PM, Luciano Coelho wrote:
> On Thu, 2013-06-27 at 14:12 -0500, Nishanth Menon wrote:
[...]
>> Indexes to another entity is always a maintenance burden in the longer
>> run and needs judicious control. If it is possible to avoid it by
>> selecting the right parameters, I am a hard advocate for the same.
>
> I tend to agree.  But you need a balance.  In theory you're right.  But
> I think if you take the real world example, it is over-engineering.
>
> Anyway, if you *really* think this needs to be changed, I think we're in
> a deadlock here and I'd like to hear other people's opinions.  I don't
> mind making the change, but I'm still not convinced it is worth it,
> since it just adds complexity.
>
> And hey, this is too much bikeshedding for such a small detail.
Lol :)

Alrite, if no one else is complaining, I am not going to block it either.

-- 
Regards,
Nishanth Menon

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Luciano Coelho]

On Fri, 2013-06-28 at 13:31 +0300, Luciano Coelho wrote:
> (fixed Mike's address)
> 
> On Fri, 2013-06-28 at 11:21 +0100, Mark Rutland wrote:
> > On Fri, Jun 28, 2013 at 10:53:35AM +0100, Luciano Coelho wrote:
> > > On Fri, 2013-06-28 at 10:38 +0100, Mark Rutland wrote:
> > > > On Tue, Jun 25, 2013 at 09:35:30AM +0100, Luciano Coelho wrote:
> > > > > +Optional properties:
> > > > > +--------------------
> > > > > +
> > > > > +- refclock: the internal WLAN reference clock frequency (required for
> > > > > +  WiLink6 and WiLink7; not used for WiLink8).  Must be one of the
> > > > > +  following:
> > > > > +	0 = 19.2 MHz
> > > > > +	1 = 26.0 MHz
> > > > > +	2 = 38.4 MHz
> > > > > +	3 = 52.0 MHz
> > > > > +	4 = 38.4 MHz, XTAL
> > > > > +	5 = 26.0 MHz, XTAL
> > > > > +
> > > > > +- tcxoclock: the internal WLAN TCXO clock frequency (required for
> > > > > +  WiLink7 not used for WiLink6 and WiLink8).  Must be one of the
> > > > > +  following:
> > > > > +	0 = 19.200 MHz
> > > > > +	1 = 26.000 MHz
> > > > > +	2 = 38.400 MHz
> > > > > +	3 = 52.000 MHz
> > > > > +	4 = 16.368 MHz
> > > > > +	5 = 32.736 MHz
> > > > > +	6 = 16.800 MHz
> > > > > +	7 = 33.600 MHz
> > > > 
> > > > This looks suspiciously like what we have the common clock bindings for:
> > > > 
> > > > refclk {
> > > > 	compatible = "fixed-clock";
> > > > 	#clock-cells = <0>;
> > > > 	clock-frequency = <19200000>;
> > > > }
> > > > 
> > > > wilink {
> > > > 	compatible = "ti,wilink7";
> > > > 	interrupt-parent = <&some_interrupt_controller>;
> > > > 	interrupts = <0 1 1>;
> > > > 	clocks = <&refclk>, <&refclk>;
> > > > 	clock-names = "refclk", "txoclk";
> > > > };
> > > > 
> > > > Could you not use them?
> > > 
> > > Hmmm... this actually does look good.  But these are internal clocks in
> > > the modules, they cannot be accessed from outside.  Does it make sense
> > > to register them with the clock framework?
> > 
> > Given we already have a common way of describing clocks, I think it
> > makes sense to use it -- people already understand the common bindings,
> > and it's less code to add add to the kernel. I don't think the fact
> > these clocks are internal should prevent us from describing them as we
> > would an external clock.
> 
> Yes, I agree with you.  Thanks for the suggestion! I think it will look
> much better.  And now that I dug a bit more into the code, I can see
> that there are only structs being populated, so there shouldn't be any
> other side-effects.

Hmmm, one thing that escaped me.  Besides the frequency, I also need a
boolean that tells if the clock is XTAL or not.  I can't figure out how
to pass this if I use the generic clock framework.  Any suggestions?

--
Luca.

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Felipe Balbi]

On Fri, Jun 28, 2013 at 02:22:11PM +0300, Luciano Coelho wrote:
> On Fri, 2013-06-28 at 13:31 +0300, Luciano Coelho wrote:
> > (fixed Mike's address)
> > 
> > On Fri, 2013-06-28 at 11:21 +0100, Mark Rutland wrote:
> > > On Fri, Jun 28, 2013 at 10:53:35AM +0100, Luciano Coelho wrote:
> > > > On Fri, 2013-06-28 at 10:38 +0100, Mark Rutland wrote:
> > > > > On Tue, Jun 25, 2013 at 09:35:30AM +0100, Luciano Coelho wrote:
> > > > > > +Optional properties:
> > > > > > +--------------------
> > > > > > +
> > > > > > +- refclock: the internal WLAN reference clock frequency (required for
> > > > > > +  WiLink6 and WiLink7; not used for WiLink8).  Must be one of the
> > > > > > +  following:
> > > > > > +	0 = 19.2 MHz
> > > > > > +	1 = 26.0 MHz
> > > > > > +	2 = 38.4 MHz
> > > > > > +	3 = 52.0 MHz
> > > > > > +	4 = 38.4 MHz, XTAL
> > > > > > +	5 = 26.0 MHz, XTAL
> > > > > > +
> > > > > > +- tcxoclock: the internal WLAN TCXO clock frequency (required for
> > > > > > +  WiLink7 not used for WiLink6 and WiLink8).  Must be one of the
> > > > > > +  following:
> > > > > > +	0 = 19.200 MHz
> > > > > > +	1 = 26.000 MHz
> > > > > > +	2 = 38.400 MHz
> > > > > > +	3 = 52.000 MHz
> > > > > > +	4 = 16.368 MHz
> > > > > > +	5 = 32.736 MHz
> > > > > > +	6 = 16.800 MHz
> > > > > > +	7 = 33.600 MHz
> > > > > 
> > > > > This looks suspiciously like what we have the common clock bindings for:
> > > > > 
> > > > > refclk {
> > > > > 	compatible = "fixed-clock";
> > > > > 	#clock-cells = <0>;
> > > > > 	clock-frequency = <19200000>;
> > > > > }
> > > > > 
> > > > > wilink {
> > > > > 	compatible = "ti,wilink7";
> > > > > 	interrupt-parent = <&some_interrupt_controller>;
> > > > > 	interrupts = <0 1 1>;
> > > > > 	clocks = <&refclk>, <&refclk>;
> > > > > 	clock-names = "refclk", "txoclk";
> > > > > };
> > > > > 
> > > > > Could you not use them?
> > > > 
> > > > Hmmm... this actually does look good.  But these are internal clocks in
> > > > the modules, they cannot be accessed from outside.  Does it make sense
> > > > to register them with the clock framework?
> > > 
> > > Given we already have a common way of describing clocks, I think it
> > > makes sense to use it -- people already understand the common bindings,
> > > and it's less code to add add to the kernel. I don't think the fact
> > > these clocks are internal should prevent us from describing them as we
> > > would an external clock.
> > 
> > Yes, I agree with you.  Thanks for the suggestion! I think it will look
> > much better.  And now that I dug a bit more into the code, I can see
> > that there are only structs being populated, so there shouldn't be any
> > other side-effects.
> 
> Hmmm, one thing that escaped me.  Besides the frequency, I also need a
> boolean that tells if the clock is XTAL or not.  I can't figure out how
> to pass this if I use the generic clock framework.  Any suggestions?

Could you use clock-output-names for that ?

XTAL clock:

refclk {
	compatible = "fixed-clock";
	#clock cells = <0>;
	clock-frequency = <19200000>;
	clock-output-names = "xtal";
};

non-XTAL clock:

refclk {
	compatible = "fixed-clock";
	#clock cells = <0>;
	clock-frequency = <19200000>;
	clock-output-names = "osc"; /* any better name ? */
};

-- 
balbi
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[PATCH] Documentation: dt: bindings: TI WiLink modules

[Luciano Coelho]

On Fri, 2013-06-28 at 14:41 +0300, Felipe Balbi wrote:
> On Fri, Jun 28, 2013 at 02:22:11PM +0300, Luciano Coelho wrote:
> > On Fri, 2013-06-28 at 13:31 +0300, Luciano Coelho wrote:
> > > (fixed Mike's address)
> > > 
> > > On Fri, 2013-06-28 at 11:21 +0100, Mark Rutland wrote:
> > > > On Fri, Jun 28, 2013 at 10:53:35AM +0100, Luciano Coelho wrote:
> > > > > On Fri, 2013-06-28 at 10:38 +0100, Mark Rutland wrote:
> > > > > > On Tue, Jun 25, 2013 at 09:35:30AM +0100, Luciano Coelho wrote:
> > > > > > > +Optional properties:
> > > > > > > +--------------------
> > > > > > > +
> > > > > > > +- refclock: the internal WLAN reference clock frequency (required for
> > > > > > > +  WiLink6 and WiLink7; not used for WiLink8).  Must be one of the
> > > > > > > +  following:
> > > > > > > +	0 = 19.2 MHz
> > > > > > > +	1 = 26.0 MHz
> > > > > > > +	2 = 38.4 MHz
> > > > > > > +	3 = 52.0 MHz
> > > > > > > +	4 = 38.4 MHz, XTAL
> > > > > > > +	5 = 26.0 MHz, XTAL
> > > > > > > +
> > > > > > > +- tcxoclock: the internal WLAN TCXO clock frequency (required for
> > > > > > > +  WiLink7 not used for WiLink6 and WiLink8).  Must be one of the
> > > > > > > +  following:
> > > > > > > +	0 = 19.200 MHz
> > > > > > > +	1 = 26.000 MHz
> > > > > > > +	2 = 38.400 MHz
> > > > > > > +	3 = 52.000 MHz
> > > > > > > +	4 = 16.368 MHz
> > > > > > > +	5 = 32.736 MHz
> > > > > > > +	6 = 16.800 MHz
> > > > > > > +	7 = 33.600 MHz
> > > > > > 
> > > > > > This looks suspiciously like what we have the common clock bindings for:
> > > > > > 
> > > > > > refclk {
> > > > > > 	compatible = "fixed-clock";
> > > > > > 	#clock-cells = <0>;
> > > > > > 	clock-frequency = <19200000>;
> > > > > > }
> > > > > > 
> > > > > > wilink {
> > > > > > 	compatible = "ti,wilink7";
> > > > > > 	interrupt-parent = <&some_interrupt_controller>;
> > > > > > 	interrupts = <0 1 1>;
> > > > > > 	clocks = <&refclk>, <&refclk>;
> > > > > > 	clock-names = "refclk", "txoclk";
> > > > > > };
> > > > > > 
> > > > > > Could you not use them?
> > > > > 
> > > > > Hmmm... this actually does look good.  But these are internal clocks in
> > > > > the modules, they cannot be accessed from outside.  Does it make sense
> > > > > to register them with the clock framework?
> > > > 
> > > > Given we already have a common way of describing clocks, I think it
> > > > makes sense to use it -- people already understand the common bindings,
> > > > and it's less code to add add to the kernel. I don't think the fact
> > > > these clocks are internal should prevent us from describing them as we
> > > > would an external clock.
> > > 
> > > Yes, I agree with you.  Thanks for the suggestion! I think it will look
> > > much better.  And now that I dug a bit more into the code, I can see
> > > that there are only structs being populated, so there shouldn't be any
> > > other side-effects.
> > 
> > Hmmm, one thing that escaped me.  Besides the frequency, I also need a
> > boolean that tells if the clock is XTAL or not.  I can't figure out how
> > to pass this if I use the generic clock framework.  Any suggestions?
> 
> Could you use clock-output-names for that ?
> 
> XTAL clock:
> 
> refclk {
> 	compatible = "fixed-clock";
> 	#clock cells = <0>;
> 	clock-frequency = <19200000>;
> 	clock-output-names = "xtal";
> };
> 
> non-XTAL clock:
> 
> refclk {
> 	compatible = "fixed-clock";
> 	#clock cells = <0>;
> 	clock-frequency = <19200000>;
> 	clock-output-names = "osc"; /* any better name ? */
> };

This starts looking a bit hacky.  Using the output name as a flag is not
very pretty.

I think it would be better to have a separate flag for it in the wlan
node.  Like an optional "refclock-xtal" boolean or something.  The
downside of this is that we would be adding information about the clock
details in the wilink node. :(

OTOH, we could add a flag to the generic clock binding? A new optional
boolean that tells whether the clock is XTAL or not:

refclk {
	compatible = "fixed-clock";
	#clock cells = <0>;
	clock-frequency = <19200000>;
	clock-xtal;
};

Do you think that would make sense?

--
Luca.

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Felipe Balbi]

On Fri, Jun 28, 2013 at 03:13:52PM +0300, Luciano Coelho wrote:
> On Fri, 2013-06-28 at 14:41 +0300, Felipe Balbi wrote:
> > On Fri, Jun 28, 2013 at 02:22:11PM +0300, Luciano Coelho wrote:
> > > On Fri, 2013-06-28 at 13:31 +0300, Luciano Coelho wrote:
> > > > (fixed Mike's address)
> > > > 
> > > > On Fri, 2013-06-28 at 11:21 +0100, Mark Rutland wrote:
> > > > > On Fri, Jun 28, 2013 at 10:53:35AM +0100, Luciano Coelho wrote:
> > > > > > On Fri, 2013-06-28 at 10:38 +0100, Mark Rutland wrote:
> > > > > > > On Tue, Jun 25, 2013 at 09:35:30AM +0100, Luciano Coelho wrote:
> > > > > > > > +Optional properties:
> > > > > > > > +--------------------
> > > > > > > > +
> > > > > > > > +- refclock: the internal WLAN reference clock frequency (required for
> > > > > > > > +  WiLink6 and WiLink7; not used for WiLink8).  Must be one of the
> > > > > > > > +  following:
> > > > > > > > +	0 = 19.2 MHz
> > > > > > > > +	1 = 26.0 MHz
> > > > > > > > +	2 = 38.4 MHz
> > > > > > > > +	3 = 52.0 MHz
> > > > > > > > +	4 = 38.4 MHz, XTAL
> > > > > > > > +	5 = 26.0 MHz, XTAL
> > > > > > > > +
> > > > > > > > +- tcxoclock: the internal WLAN TCXO clock frequency (required for
> > > > > > > > +  WiLink7 not used for WiLink6 and WiLink8).  Must be one of the
> > > > > > > > +  following:
> > > > > > > > +	0 = 19.200 MHz
> > > > > > > > +	1 = 26.000 MHz
> > > > > > > > +	2 = 38.400 MHz
> > > > > > > > +	3 = 52.000 MHz
> > > > > > > > +	4 = 16.368 MHz
> > > > > > > > +	5 = 32.736 MHz
> > > > > > > > +	6 = 16.800 MHz
> > > > > > > > +	7 = 33.600 MHz
> > > > > > > 
> > > > > > > This looks suspiciously like what we have the common clock bindings for:
> > > > > > > 
> > > > > > > refclk {
> > > > > > > 	compatible = "fixed-clock";
> > > > > > > 	#clock-cells = <0>;
> > > > > > > 	clock-frequency = <19200000>;
> > > > > > > }
> > > > > > > 
> > > > > > > wilink {
> > > > > > > 	compatible = "ti,wilink7";
> > > > > > > 	interrupt-parent = <&some_interrupt_controller>;
> > > > > > > 	interrupts = <0 1 1>;
> > > > > > > 	clocks = <&refclk>, <&refclk>;
> > > > > > > 	clock-names = "refclk", "txoclk";
> > > > > > > };
> > > > > > > 
> > > > > > > Could you not use them?
> > > > > > 
> > > > > > Hmmm... this actually does look good.  But these are internal clocks in
> > > > > > the modules, they cannot be accessed from outside.  Does it make sense
> > > > > > to register them with the clock framework?
> > > > > 
> > > > > Given we already have a common way of describing clocks, I think it
> > > > > makes sense to use it -- people already understand the common bindings,
> > > > > and it's less code to add add to the kernel. I don't think the fact
> > > > > these clocks are internal should prevent us from describing them as we
> > > > > would an external clock.
> > > > 
> > > > Yes, I agree with you.  Thanks for the suggestion! I think it will look
> > > > much better.  And now that I dug a bit more into the code, I can see
> > > > that there are only structs being populated, so there shouldn't be any
> > > > other side-effects.
> > > 
> > > Hmmm, one thing that escaped me.  Besides the frequency, I also need a
> > > boolean that tells if the clock is XTAL or not.  I can't figure out how
> > > to pass this if I use the generic clock framework.  Any suggestions?
> > 
> > Could you use clock-output-names for that ?
> > 
> > XTAL clock:
> > 
> > refclk {
> > 	compatible = "fixed-clock";
> > 	#clock cells = <0>;
> > 	clock-frequency = <19200000>;
> > 	clock-output-names = "xtal";
> > };
> > 
> > non-XTAL clock:
> > 
> > refclk {
> > 	compatible = "fixed-clock";
> > 	#clock cells = <0>;
> > 	clock-frequency = <19200000>;
> > 	clock-output-names = "osc"; /* any better name ? */
> > };
> 
> This starts looking a bit hacky.  Using the output name as a flag is not
> very pretty.
> 
> I think it would be better to have a separate flag for it in the wlan
> node.  Like an optional "refclock-xtal" boolean or something.  The
> downside of this is that we would be adding information about the clock
> details in the wilink node. :(
> 
> OTOH, we could add a flag to the generic clock binding? A new optional
> boolean that tells whether the clock is XTAL or not:
> 
> refclk {
> 	compatible = "fixed-clock";
> 	#clock cells = <0>;
> 	clock-frequency = <19200000>;
> 	clock-xtal;
> };
> 
> Do you think that would make sense?

sure, that looks alright to me. Surely there are other devices out there
who want to know if the clock comes from a crystal or not ?!?

cheers

-- 
balbi
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[PATCH] Documentation: dt: bindings: TI WiLink modules

[Luciano Coelho]

On Fri, 2013-06-28 at 15:18 +0300, Felipe Balbi wrote:
> On Fri, Jun 28, 2013 at 03:13:52PM +0300, Luciano Coelho wrote:
> > On Fri, 2013-06-28 at 14:41 +0300, Felipe Balbi wrote:
> > > On Fri, Jun 28, 2013 at 02:22:11PM +0300, Luciano Coelho wrote:
> > > > On Fri, 2013-06-28 at 13:31 +0300, Luciano Coelho wrote:
> > > > > (fixed Mike's address)
> > > > > 
> > > > > On Fri, 2013-06-28 at 11:21 +0100, Mark Rutland wrote:
> > > > > > On Fri, Jun 28, 2013 at 10:53:35AM +0100, Luciano Coelho wrote:
> > > > > > > On Fri, 2013-06-28 at 10:38 +0100, Mark Rutland wrote:
> > > > > > > > On Tue, Jun 25, 2013 at 09:35:30AM +0100, Luciano Coelho wrote:
> > > > > > > > > +Optional properties:
> > > > > > > > > +--------------------
> > > > > > > > > +
> > > > > > > > > +- refclock: the internal WLAN reference clock frequency (required for
> > > > > > > > > +  WiLink6 and WiLink7; not used for WiLink8).  Must be one of the
> > > > > > > > > +  following:
> > > > > > > > > +	0 = 19.2 MHz
> > > > > > > > > +	1 = 26.0 MHz
> > > > > > > > > +	2 = 38.4 MHz
> > > > > > > > > +	3 = 52.0 MHz
> > > > > > > > > +	4 = 38.4 MHz, XTAL
> > > > > > > > > +	5 = 26.0 MHz, XTAL
> > > > > > > > > +
> > > > > > > > > +- tcxoclock: the internal WLAN TCXO clock frequency (required for
> > > > > > > > > +  WiLink7 not used for WiLink6 and WiLink8).  Must be one of the
> > > > > > > > > +  following:
> > > > > > > > > +	0 = 19.200 MHz
> > > > > > > > > +	1 = 26.000 MHz
> > > > > > > > > +	2 = 38.400 MHz
> > > > > > > > > +	3 = 52.000 MHz
> > > > > > > > > +	4 = 16.368 MHz
> > > > > > > > > +	5 = 32.736 MHz
> > > > > > > > > +	6 = 16.800 MHz
> > > > > > > > > +	7 = 33.600 MHz
> > > > > > > > 
> > > > > > > > This looks suspiciously like what we have the common clock bindings for:
> > > > > > > > 
> > > > > > > > refclk {
> > > > > > > > 	compatible = "fixed-clock";
> > > > > > > > 	#clock-cells = <0>;
> > > > > > > > 	clock-frequency = <19200000>;
> > > > > > > > }
> > > > > > > > 
> > > > > > > > wilink {
> > > > > > > > 	compatible = "ti,wilink7";
> > > > > > > > 	interrupt-parent = <&some_interrupt_controller>;
> > > > > > > > 	interrupts = <0 1 1>;
> > > > > > > > 	clocks = <&refclk>, <&refclk>;
> > > > > > > > 	clock-names = "refclk", "txoclk";
> > > > > > > > };
> > > > > > > > 
> > > > > > > > Could you not use them?
> > > > > > > 
> > > > > > > Hmmm... this actually does look good.  But these are internal clocks in
> > > > > > > the modules, they cannot be accessed from outside.  Does it make sense
> > > > > > > to register them with the clock framework?
> > > > > > 
> > > > > > Given we already have a common way of describing clocks, I think it
> > > > > > makes sense to use it -- people already understand the common bindings,
> > > > > > and it's less code to add add to the kernel. I don't think the fact
> > > > > > these clocks are internal should prevent us from describing them as we
> > > > > > would an external clock.
> > > > > 
> > > > > Yes, I agree with you.  Thanks for the suggestion! I think it will look
> > > > > much better.  And now that I dug a bit more into the code, I can see
> > > > > that there are only structs being populated, so there shouldn't be any
> > > > > other side-effects.
> > > > 
> > > > Hmmm, one thing that escaped me.  Besides the frequency, I also need a
> > > > boolean that tells if the clock is XTAL or not.  I can't figure out how
> > > > to pass this if I use the generic clock framework.  Any suggestions?
> > > 
> > > Could you use clock-output-names for that ?
> > > 
> > > XTAL clock:
> > > 
> > > refclk {
> > > 	compatible = "fixed-clock";
> > > 	#clock cells = <0>;
> > > 	clock-frequency = <19200000>;
> > > 	clock-output-names = "xtal";
> > > };
> > > 
> > > non-XTAL clock:
> > > 
> > > refclk {
> > > 	compatible = "fixed-clock";
> > > 	#clock cells = <0>;
> > > 	clock-frequency = <19200000>;
> > > 	clock-output-names = "osc"; /* any better name ? */
> > > };
> > 
> > This starts looking a bit hacky.  Using the output name as a flag is not
> > very pretty.
> > 
> > I think it would be better to have a separate flag for it in the wlan
> > node.  Like an optional "refclock-xtal" boolean or something.  The
> > downside of this is that we would be adding information about the clock
> > details in the wilink node. :(
> > 
> > OTOH, we could add a flag to the generic clock binding? A new optional
> > boolean that tells whether the clock is XTAL or not:
> > 
> > refclk {
> > 	compatible = "fixed-clock";
> > 	#clock cells = <0>;
> > 	clock-frequency = <19200000>;
> > 	clock-xtal;
> > };
> > 
> > Do you think that would make sense?
> 
> sure, that looks alright to me. Surely there are other devices out there
> who want to know if the clock comes from a crystal or not ?!?

Mike, what do you think about this idea? If it sounds okay to you, I can
cook up a patch adding this flag.

--
Cheers,
Luca.

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Luciano Coelho]

On Fri, 2013-06-28 at 16:21 +0300, Luciano Coelho wrote:
> On Fri, 2013-06-28 at 15:18 +0300, Felipe Balbi wrote:
> > On Fri, Jun 28, 2013 at 03:13:52PM +0300, Luciano Coelho wrote:
> > > On Fri, 2013-06-28 at 14:41 +0300, Felipe Balbi wrote:
> > > > On Fri, Jun 28, 2013 at 02:22:11PM +0300, Luciano Coelho wrote:
> > > > > On Fri, 2013-06-28 at 13:31 +0300, Luciano Coelho wrote:
> > > > > > (fixed Mike's address)
> > > > > > 
> > > > > > On Fri, 2013-06-28 at 11:21 +0100, Mark Rutland wrote:
> > > > > > > On Fri, Jun 28, 2013 at 10:53:35AM +0100, Luciano Coelho wrote:
> > > > > > > > On Fri, 2013-06-28 at 10:38 +0100, Mark Rutland wrote:
> > > > > > > > > On Tue, Jun 25, 2013 at 09:35:30AM +0100, Luciano Coelho wrote:
> > > > > > > > > > +Optional properties:
> > > > > > > > > > +--------------------
> > > > > > > > > > +
> > > > > > > > > > +- refclock: the internal WLAN reference clock frequency (required for
> > > > > > > > > > +  WiLink6 and WiLink7; not used for WiLink8).  Must be one of the
> > > > > > > > > > +  following:
> > > > > > > > > > +	0 = 19.2 MHz
> > > > > > > > > > +	1 = 26.0 MHz
> > > > > > > > > > +	2 = 38.4 MHz
> > > > > > > > > > +	3 = 52.0 MHz
> > > > > > > > > > +	4 = 38.4 MHz, XTAL
> > > > > > > > > > +	5 = 26.0 MHz, XTAL
> > > > > > > > > > +
> > > > > > > > > > +- tcxoclock: the internal WLAN TCXO clock frequency (required for
> > > > > > > > > > +  WiLink7 not used for WiLink6 and WiLink8).  Must be one of the
> > > > > > > > > > +  following:
> > > > > > > > > > +	0 = 19.200 MHz
> > > > > > > > > > +	1 = 26.000 MHz
> > > > > > > > > > +	2 = 38.400 MHz
> > > > > > > > > > +	3 = 52.000 MHz
> > > > > > > > > > +	4 = 16.368 MHz
> > > > > > > > > > +	5 = 32.736 MHz
> > > > > > > > > > +	6 = 16.800 MHz
> > > > > > > > > > +	7 = 33.600 MHz
> > > > > > > > > 
> > > > > > > > > This looks suspiciously like what we have the common clock bindings for:
> > > > > > > > > 
> > > > > > > > > refclk {
> > > > > > > > > 	compatible = "fixed-clock";
> > > > > > > > > 	#clock-cells = <0>;
> > > > > > > > > 	clock-frequency = <19200000>;
> > > > > > > > > }
> > > > > > > > > 
> > > > > > > > > wilink {
> > > > > > > > > 	compatible = "ti,wilink7";
> > > > > > > > > 	interrupt-parent = <&some_interrupt_controller>;
> > > > > > > > > 	interrupts = <0 1 1>;
> > > > > > > > > 	clocks = <&refclk>, <&refclk>;
> > > > > > > > > 	clock-names = "refclk", "txoclk";
> > > > > > > > > };
> > > > > > > > > 
> > > > > > > > > Could you not use them?
> > > > > > > > 
> > > > > > > > Hmmm... this actually does look good.  But these are internal clocks in
> > > > > > > > the modules, they cannot be accessed from outside.  Does it make sense
> > > > > > > > to register them with the clock framework?
> > > > > > > 
> > > > > > > Given we already have a common way of describing clocks, I think it
> > > > > > > makes sense to use it -- people already understand the common bindings,
> > > > > > > and it's less code to add add to the kernel. I don't think the fact
> > > > > > > these clocks are internal should prevent us from describing them as we
> > > > > > > would an external clock.
> > > > > > 
> > > > > > Yes, I agree with you.  Thanks for the suggestion! I think it will look
> > > > > > much better.  And now that I dug a bit more into the code, I can see
> > > > > > that there are only structs being populated, so there shouldn't be any
> > > > > > other side-effects.
> > > > > 
> > > > > Hmmm, one thing that escaped me.  Besides the frequency, I also need a
> > > > > boolean that tells if the clock is XTAL or not.  I can't figure out how
> > > > > to pass this if I use the generic clock framework.  Any suggestions?
> > > > 
> > > > Could you use clock-output-names for that ?
> > > > 
> > > > XTAL clock:
> > > > 
> > > > refclk {
> > > > 	compatible = "fixed-clock";
> > > > 	#clock cells = <0>;
> > > > 	clock-frequency = <19200000>;
> > > > 	clock-output-names = "xtal";
> > > > };
> > > > 
> > > > non-XTAL clock:
> > > > 
> > > > refclk {
> > > > 	compatible = "fixed-clock";
> > > > 	#clock cells = <0>;
> > > > 	clock-frequency = <19200000>;
> > > > 	clock-output-names = "osc"; /* any better name ? */
> > > > };
> > > 
> > > This starts looking a bit hacky.  Using the output name as a flag is not
> > > very pretty.
> > > 
> > > I think it would be better to have a separate flag for it in the wlan
> > > node.  Like an optional "refclock-xtal" boolean or something.  The
> > > downside of this is that we would be adding information about the clock
> > > details in the wilink node. :(
> > > 
> > > OTOH, we could add a flag to the generic clock binding? A new optional
> > > boolean that tells whether the clock is XTAL or not:
> > > 
> > > refclk {
> > > 	compatible = "fixed-clock";
> > > 	#clock cells = <0>;
> > > 	clock-frequency = <19200000>;
> > > 	clock-xtal;
> > > };
> > > 
> > > Do you think that would make sense?
> > 
> > sure, that looks alright to me. Surely there are other devices out there
> > who want to know if the clock comes from a crystal or not ?!?
> 
> Mike, what do you think about this idea? If it sounds okay to you, I can
> cook up a patch adding this flag.

Hmmm... I started implementing this whole thing, but using these clocks
as "fixed-clock"s is not so straightforward.  The problem is that I
would need to register my driver as a clock provider and add the OF
match for "fixed-clock".

If I do that, all the other "fixed-clock" nodes would be passed to my
driver too, which is wrong.  Or, the platform should register the
"fixed-clock" match, but this would be wrong too, since it would find
*my* fixed-clocks.

The only thing I can come up with is to make a small clock driver (maybe
even inside the WiLink module itself) that registers a new type of
clock, "ti,wilink-clock" or something.  But this would really be
overkill, wouldn't it?

Any other ideas?

--
Luca.

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Laurent Pinchart]

Hi Luciano,

On Monday 01 July 2013 15:39:30 Luciano Coelho wrote:
> On Fri, 2013-06-28 at 16:21 +0300, Luciano Coelho wrote:
> > On Fri, 2013-06-28 at 15:18 +0300, Felipe Balbi wrote:
> > > On Fri, Jun 28, 2013 at 03:13:52PM +0300, Luciano Coelho wrote:
> > > > On Fri, 2013-06-28 at 14:41 +0300, Felipe Balbi wrote:
> > > > > On Fri, Jun 28, 2013 at 02:22:11PM +0300, Luciano Coelho wrote:
> > > > > > On Fri, 2013-06-28 at 13:31 +0300, Luciano Coelho wrote:
> > > > > > > (fixed Mike's address)
> > > > > > > 
> > > > > > > On Fri, 2013-06-28 at 11:21 +0100, Mark Rutland wrote:
> > > > > > > > On Fri, Jun 28, 2013 at 10:53:35AM +0100, Luciano Coelho 
wrote:
> > > > > > > > > On Fri, 2013-06-28 at 10:38 +0100, Mark Rutland wrote:
> > > > > > > > > > On Tue, Jun 25, 2013 at 09:35:30AM +0100, Luciano Coelho 
wrote:
> > > > > > > > > > > +Optional properties:
> > > > > > > > > > > +--------------------
> > > > > > > > > > > +
> > > > > > > > > > > +- refclock: the internal WLAN reference clock frequency
> > > > > > > > > > > (required for
> > > > > > > > > > > +  WiLink6 and WiLink7; not used for WiLink8).  Must be
> > > > > > > > > > > one of the
> > > > > > > > > > > +  following:
> > > > > > > > > > > +	0 = 19.2 MHz
> > > > > > > > > > > +	1 = 26.0 MHz
> > > > > > > > > > > +	2 = 38.4 MHz
> > > > > > > > > > > +	3 = 52.0 MHz
> > > > > > > > > > > +	4 = 38.4 MHz, XTAL
> > > > > > > > > > > +	5 = 26.0 MHz, XTAL
> > > > > > > > > > > +
> > > > > > > > > > > +- tcxoclock: the internal WLAN TCXO clock frequency
> > > > > > > > > > > (required for
> > > > > > > > > > > +  WiLink7 not used for WiLink6 and WiLink8).  Must be
> > > > > > > > > > > one of the
> > > > > > > > > > > +  following:
> > > > > > > > > > > +	0 = 19.200 MHz
> > > > > > > > > > > +	1 = 26.000 MHz
> > > > > > > > > > > +	2 = 38.400 MHz
> > > > > > > > > > > +	3 = 52.000 MHz
> > > > > > > > > > > +	4 = 16.368 MHz
> > > > > > > > > > > +	5 = 32.736 MHz
> > > > > > > > > > > +	6 = 16.800 MHz
> > > > > > > > > > > +	7 = 33.600 MHz
> > > > > > > > > > 
> > > > > > > > > > This looks suspiciously like what we have the common clock
> > > > > > > > > > bindings for:
> > > > > > > > > > 
> > > > > > > > > > refclk {
> > > > > > > > > > 
> > > > > > > > > > 	compatible = "fixed-clock";
> > > > > > > > > > 	#clock-cells = <0>;
> > > > > > > > > > 	clock-frequency = <19200000>;
> > > > > > > > > > 
> > > > > > > > > > }
> > > > > > > > > > 
> > > > > > > > > > wilink {
> > > > > > > > > > 
> > > > > > > > > > 	compatible = "ti,wilink7";
> > > > > > > > > > 	interrupt-parent = <&some_interrupt_controller>;
> > > > > > > > > > 	interrupts = <0 1 1>;
> > > > > > > > > > 	clocks = <&refclk>, <&refclk>;
> > > > > > > > > > 	clock-names = "refclk", "txoclk";
> > > > > > > > > > 
> > > > > > > > > > };
> > > > > > > > > > 
> > > > > > > > > > Could you not use them?
> > > > > > > > > 
> > > > > > > > > Hmmm... this actually does look good.  But these are
> > > > > > > > > internal clocks in the modules, they cannot be accessed from
> > > > > > > > > outside.  Does it make sense to register them with the clock
> > > > > > > > > framework?
> > > > > > > > 
> > > > > > > > Given we already have a common way of describing clocks, I
> > > > > > > > think it makes sense to use it -- people already understand
> > > > > > > > the common bindings, and it's less code to add add to the
> > > > > > > > kernel. I don't think the fact these clocks are internal
> > > > > > > > should prevent us from describing them as we would an external
> > > > > > > > clock.
> > > > > > > 
> > > > > > > Yes, I agree with you.  Thanks for the suggestion! I think it
> > > > > > > will look much better.  And now that I dug a bit more into the
> > > > > > > code, I can see that there are only structs being populated, so
> > > > > > > there shouldn't be any other side-effects.
> > > > > > 
> > > > > > Hmmm, one thing that escaped me.  Besides the frequency, I also
> > > > > > need a boolean that tells if the clock is XTAL or not.  I can't
> > > > > > figure out how to pass this if I use the generic clock framework. 
> > > > > > Any suggestions?
> > > > > 
> > > > > Could you use clock-output-names for that ?
> > > > > 
> > > > > XTAL clock:
> > > > > 
> > > > > refclk {
> > > > > 
> > > > > 	compatible = "fixed-clock";
> > > > > 	#clock cells = <0>;
> > > > > 	clock-frequency = <19200000>;
> > > > > 	clock-output-names = "xtal";
> > > > > 
> > > > > };
> > > > > 
> > > > > non-XTAL clock:
> > > > > 
> > > > > refclk {
> > > > > 
> > > > > 	compatible = "fixed-clock";
> > > > > 	#clock cells = <0>;
> > > > > 	clock-frequency = <19200000>;
> > > > > 	clock-output-names = "osc"; /* any better name ? */
> > > > > 
> > > > > };
> > > > 
> > > > This starts looking a bit hacky.  Using the output name as a flag is
> > > > not very pretty.
> > > > 
> > > > I think it would be better to have a separate flag for it in the wlan
> > > > node.  Like an optional "refclock-xtal" boolean or something.  The
> > > > downside of this is that we would be adding information about the
> > > > clock details in the wilink node. :(
> > > > 
> > > > OTOH, we could add a flag to the generic clock binding? A new optional
> > > > boolean that tells whether the clock is XTAL or not:
> > > > 
> > > > refclk {
> > > > 
> > > > 	compatible = "fixed-clock";
> > > > 	#clock cells = <0>;
> > > > 	clock-frequency = <19200000>;
> > > > 	clock-xtal;
> > > > 
> > > > };
> > > > 
> > > > Do you think that would make sense?
> > > 
> > > sure, that looks alright to me. Surely there are other devices out there
> > > who want to know if the clock comes from a crystal or not ?!?
> > 
> > Mike, what do you think about this idea? If it sounds okay to you, I can
> > cook up a patch adding this flag.
> 
> Hmmm... I started implementing this whole thing, but using these clocks
> as "fixed-clock"s is not so straightforward.  The problem is that I
> would need to register my driver as a clock provider and add the OF
> match for "fixed-clock".
> 
> If I do that, all the other "fixed-clock" nodes would be passed to my
> driver too, which is wrong.  Or, the platform should register the
> "fixed-clock" match, but this would be wrong too, since it would find
> *my* fixed-clocks.
> 
> The only thing I can come up with is to make a small clock driver (maybe
> even inside the WiLink module itself) that registers a new type of
> clock, "ti,wilink-clock" or something.  But this would really be
> overkill, wouldn't it?
> 
> Any other ideas?

One possibility would be to just call clk_get_rate() on the clock from the 
WiLink driver, which would return the fixed frequency specified in DT, and 
configure the WiLink hardware accordingly. This might be a bit hackish though.

-- 
Regards,

Laurent Pinchart

[PATCH] Documentation: dt: bindings: TI WiLink modules

[Luciano Coelho]

On Thu, 2013-07-18 at 01:58 +0200, Laurent Pinchart wrote:
> Hi Luciano,

Hi Laurent,

> On Monday 01 July 2013 15:39:30 Luciano Coelho wrote:
> > The only thing I can come up with is to make a small clock driver (maybe
> > even inside the WiLink module itself) that registers a new type of
> > clock, "ti,wilink-clock" or something.  But this would really be
> > overkill, wouldn't it?
> > 
> > Any other ideas?
> 
> One possibility would be to just call clk_get_rate() on the clock from the 
> WiLink driver, which would return the fixed frequency specified in DT, and 
> configure the WiLink hardware accordingly. This might be a bit hackish though.

The problem is not get the rate itself, the problem is knowing whether
the clock is XTAL or not.  The WiLink chip uses the clock in a slightly
different way if it is XTAL, due to some stabilization time constraints.

--
Luca.