[PATCH v14 07/16] dt-bindings: fix sifive gpio properties
Damien Le Moal
Damien.LeMoal at wdc.com
Fri Feb 5 18:32:01 EST 2021
On Fri, 2021-02-05 at 17:55 -0500, Sean Anderson wrote:
> On 2/5/21 5:53 PM, Damien Le Moal wrote:
> > On Fri, 2021-02-05 at 14:02 -0600, Rob Herring wrote:
> > > On Wed, Feb 3, 2021 at 6:47 PM Damien Le Moal <Damien.LeMoal at wdc.com> wrote:
> > > >
> > > > On Wed, 2021-02-03 at 14:41 -0600, Rob Herring wrote:
> > > > > On Wed, Feb 3, 2021 at 6:52 AM Damien Le Moal <Damien.LeMoal at wdc.com> wrote:
> > > > > >
> > > > > > On Tue, 2021-02-02 at 13:02 -0600, Rob Herring wrote:
> > > > > > > On Tue, Feb 2, 2021 at 4:36 AM Damien Le Moal <damien.lemoal at wdc.com> wrote:
> > > > > > > >
> > > > > > > > The sifive gpio IP block supports up to 32 GPIOs. Reflect that in the
> > > > > > > > interrupts property description and maxItems. Also add the standard
> > > > > > > > ngpios property to describe the number of GPIOs available on the
> > > > > > > > implementation.
> > > > > > > >
> > > > > > > > Also add the "canaan,k210-gpiohs" compatible string to indicate the use
> > > > > > > > of this gpio controller in the Canaan Kendryte K210 SoC. If this
> > > > > > > > compatible string is used, do not define the clocks property as
> > > > > > > > required as the K210 SoC does not have a software controllable clock
> > > > > > > > for the Sifive gpio IP block.
> > > > > > > >
> > > > > > > > Cc: Paul Walmsley <paul.walmsley at sifive.com>
> > > > > > > > Cc: Rob Herring <robh at kernel.org>
> > > > > > > > Cc: devicetree at vger.kernel.org
> > > > > > > > Signed-off-by: Damien Le Moal <damien.lemoal at wdc.com>
> > > > > > > > ---
> > > > > > > > .../devicetree/bindings/gpio/sifive,gpio.yaml | 21 ++++++++++++++++---
> > > > > > > > 1 file changed, 18 insertions(+), 3 deletions(-)
> > > > > > > >
> > > > > > > > diff --git a/Documentation/devicetree/bindings/gpio/sifive,gpio.yaml b/Documentation/devicetree/bindings/gpio/sifive,gpio.yaml
> > > > > > > > index ab22056f8b44..2cef18ca737c 100644
> > > > > > > > --- a/Documentation/devicetree/bindings/gpio/sifive,gpio.yaml
> > > > > > > > +++ b/Documentation/devicetree/bindings/gpio/sifive,gpio.yaml
> > > > > > > > @@ -16,6 +16,7 @@ properties:
> > > > > > > > - enum:
> > > > > > > > - sifive,fu540-c000-gpio
> > > > > > > > - sifive,fu740-c000-gpio
> > > > > > > > + - canaan,k210-gpiohs
> > > > > > > > - const: sifive,gpio0
> > > > > > > >
> > > > > > > > reg:
> > > > > > > > @@ -23,9 +24,9 @@ properties:
> > > > > > > >
> > > > > > > > interrupts:
> > > > > > > > description:
> > > > > > > > - interrupt mapping one per GPIO. Maximum 16 GPIOs.
> > > > > > > > + interrupt mapping one per GPIO. Maximum 32 GPIOs.
> > > > > > > > minItems: 1
> > > > > > > > - maxItems: 16
> > > > > > > > + maxItems: 32
> > > > > > > >
> > > > > > > > interrupt-controller: true
> > > > > > > >
> > > > > > > > @@ -38,6 +39,10 @@ properties:
> > > > > > > > "#gpio-cells":
> > > > > > > > const: 2
> > > > > > > >
> > > > > > > > + ngpios:
> > > > > > > > + minimum: 1
> > > > > > > > + maximum: 32
> > > > > > >
> > > > > > > What's the default as obviously drivers already assume something.
> > > > > > >
> > > > > > > Does a driver actually need to know this? For example, does the
> > > > > > > register stride change or something?
> > > > > > >
> > > > > > > Please don't add it if the only purpose is error check your DT (IOW,
> > > > > > > if it just checks the max cell value in gpios phandles).
> > > > > >
> > > > > > If I remove that, make dtbs_check complains. Looking at othe gpio controller
> > > > > > bindings, they all have it. So isn't it better to be consistent, and avoid make
> > > > > > dtbs_check errors ?
> > > > >
> > > > > That would mean you are already using 'ngpios' and it is undocumented
> > > > > (for this binding). If already in use and possibly having users then
> > > > > that changes things, but that's not what the commit msg says.
> > > > >
> > > > > Not *all* gpio controllers have ngpios. It's a good number, but
> > > > > probably more than need it though. If we wanted it everywhere, there
> > > > > would be a schema enforcing that.
> > > >
> > > > If I remove the minimum and maximum lines, I get this error:
> > >
> > > I never said remove minimum/maximum. The suggestion is either add
> > > 'default: 16' or remove 'ngpios' entirely.
> > >
> > > > ./Documentation/devicetree/bindings/gpio/sifive,gpio.yaml:42:10: [error] empty
> > > > value in block mapping (empty-values)
> > > > CHKDT Documentation/devicetree/bindings/processed-schema-examples.json
> > > > /home/damien/Projects/RISCV/linux/Documentation/devicetree/bindings/gpio/sifive
> > > > ,gpio.yaml: properties:ngpios: None is not of type 'object', 'boolean'
> > > > SCHEMA Documentation/devicetree/bindings/processed-schema-examples.json
> > > > /home/damien/Projects/RISCV/linux/Documentation/devicetree/bindings/gpio/sifive
> > > > ,gpio.yaml: ignoring, error in schema: properties: ngpios
> > > > warning: no schema found in file:
> > > > ./Documentation/devicetree/bindings/gpio/sifive,gpio.yaml
> > >
> > > ngpios: true
> > >
> > > or
> > >
> > > ngpios: {}
> > >
> > > Are the minimum valid values for a key. (Though not what should be done here.)
> > >
> > > >
> > > > If I remove the ngpios property entirely, then I get a hit on the device tree:
> > > >
> > > > CHECK arch/riscv/boot/dts/canaan/sipeed_maix_bit.dt.yaml
> > > > /linux/arch/riscv/boot/dts/canaan/sipeed_maix_bit.dt.yaml:
> > > > gpio-controller at 38001000: 'ngpios' does not match any of the regexes: 'pinctrl-
> > > > [0-9]+'
> > > > From schema:
> > > > /home/damien/Projects/RISCV/linux/Documentation/devicetree/bindings/gpio/sifive
> > > > ,gpio.yaml
> > >
> > > That's not upstream, right? Then fix it.
> > >
> > > > Now, If I change the property definition to this:
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/gpio/sifive,gpio.yaml
> > > > b/Documentation/devicetree/bindings/gpio/sifive,gpio.yaml
> > > > index 2cef18ca737c..5c7865180383 100644
> > > > --- a/Documentation/devicetree/bindings/gpio/sifive,gpio.yaml
> > > > +++ b/Documentation/devicetree/bindings/gpio/sifive,gpio.yaml
> > > > @@ -40,8 +40,11 @@ properties:
> > > > const: 2
> > > >
> > > > ngpios:
> > > > - minimum: 1
> > > > - maximum: 32
> > > > + $ref: /schemas/types.yaml#/definitions/uint32
> > > > + description:
> > > > + The number of GPIO pins implemented by the controller.
> > > > + It is 16 for the SiFive SoCs and 32 for the Canaan K210 SoC.
> > > > +
> > > >
> > > > gpio-controller: true
> > > >
> > > > Then all is OK.
> > > >
> > > > Which option should I go for here ? If we want to avoid a dtbs_check error, as
> > > > far as I can see, we can:
> > > > 1) Remove the ngpios property and remove its use from the DTS, which is not
> > > > nice in my opinion
> > >
> > > Again, it depends if there are users depending on it. A user being a
> > > GPIO driver somewhere, not a DTS file. The GPIO driver in the kernel
> > > doesn't need it. So u-boot? BSD?
> >
> > The Linux driver uses the number of interrupts for the number of gpios but
> > upstream U-Boot uses the ngpios property. So I will change this to use
> > "default: 16" as you suggested.
>
> There is no reasonable default for this hardware. I would much rather
> you keep the schema as-is, or at least go with the second option.
Since the SiFive official doc seems to say "16" as the number of gpio for this
controller, we could assume that to be the default. No ? But I agree that
clearly, the implementation can be hacked to have any number of GPIOs...
>
> --Sean
>
> >
> > Thanks !
> >
> > >
> > > > 2) Use the modification proposed above
> >
>
--
Damien Le Moal
Western Digital Research
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