Dear Mike Dunn, > On 09/15/2013 07:07 AM, Marek Vasut wrote: > > Dear Mike Dunn, > > > >> This patch adds device tree support to the PXA's PWM driver. Only an OF > >> match table is added; nothing needs to be extracted from the device tree > >> node. The existing ID table is reused for the match table data. > >> > >> Tested on a Palm Treo 680 (both platform data and DT cases). > >> > >> Signed-off-by: Mike Dunn <mikedunn@xxxxxxxxxxx> > >> --- > >> Changle log: > >> v3: > >> - remove support for the polarity flag > >> - remove per-chip pwm index cell; define custom of_xlate() > >> > >> (now #pwm-cells = <1>) > >> > >> - "compatible" strings for all devices added to OF match table > >> - various stylistic changes recommended by reviewers > >> > >> v2: > >> - of_match_table contains only the "pxa250-pwm" compatible string; > >> require one device instance per pwm > >> - add Documentation/devicetree/bindings/pwm/pxa-pwm.txt > >> - add support for polarity flag in DT and implement set_polarity() > >> method > >> > >> (the treo 680 inverts the signal between pwm out and backlight) > >> > >> - return -EINVAL instead of -ENODEV if platform data or DT node not > >> found - output dev_info string if platform data missing > >> - expanded CC list of patch > >> > >> Documentation/devicetree/bindings/pwm/pxa-pwm.txt | 31 ++++++++++++ > >> arch/arm/boot/dts/pxa27x.dtsi | 24 +++++++++ > >> drivers/pwm/pwm-pxa.c | 62 > >> > >> +++++++++++++++++++++++ 3 files changed, 117 insertions(+) > >> > >> create mode 100644 Documentation/devicetree/bindings/pwm/pxa-pwm.txt > >> > >> diff --git a/Documentation/devicetree/bindings/pwm/pxa-pwm.txt > >> b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt new file mode 100644 > >> index 0000000..6fcf90c > >> --- /dev/null > >> +++ b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt > >> @@ -0,0 +1,31 @@ > >> +Marvell PWM controller > >> + > >> +Required properties: > >> +- compatible: should be one of: > >> + - "marvell,pxa250-pwm" > >> + - "marvell,pxa270-pwm" > >> + - "marvell,pxa168-pwm" > >> + - "marvell,pxa910-pwm" > > > > This really is something I dont quite understand. Why should the driver > > list _every_ _single_ existing CPU that contains such PWM block? Is > > there any agreement about that? For me, it'd make much more sense to > > list only the CPUs where the IP block actually changed in some way, so > > that the differences can be discerned that way. > > I believe that this was Stephen's suggestion. > > I actually don't object myself. For the price of a few strings, it > - clearly shows which SoCs the driver supports > - ensures that any future differences are handled cleanly (e.g., if a hw > bug in one is discovered and a work-around is implemented) > - keeps thngs clean if support for another processor which does have pwm hw > differences is added > > Especially the third point... otherwise, you have the case of a somewhat > confusing many-to-one mapping of processors to compatible strings. OK, to push it ad-absurdum, shall we not start listing every single revision of the CPU as well ? Like pxa250a0 250a1 etc ? Yes , this many-to-one mapping is something I don't quite understand, that's why I'd love to see a good reasoning from Stephen. Best regards, Marek Vasut -- 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
