RE: [PATCH] dt-bindings: timer: gpt: update binding doc

[Anson Huang]

Hi, Rob

Best Regards!
Anson Huang

> -----Original Message-----
> From: Rob Herring [mailto:robh@xxxxxxxxxx]
> Sent: 2018年12月12日 5:35
> To: Anson Huang <anson.huang@xxxxxxx>
> Cc: daniel.lezcano@xxxxxxxxxx; tglx@xxxxxxxxxxxxx; mark.rutland@xxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; dl-linux-imx
> <linux-imx@xxxxxxx>
> Subject: Re: [PATCH] dt-bindings: timer: gpt: update binding doc
> 
> On Fri, Nov 23, 2018 at 09:10:09AM +0000, Anson Huang wrote:
> > The i.MX GPT timer driver binding doc is out of date, the
> > "interrupts", "clocks" and "clock-names" do NOT match current GPT
> > driver implementation, update it and use i.MX6SX as example.
> >
> > Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>
> > ---
> >  .../devicetree/bindings/timer/fsl,imxgpt.txt       | 22
> +++++++++++++---------
> >  1 file changed, 13 insertions(+), 9 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/timer/fsl,imxgpt.txt
> > b/Documentation/devicetree/bindings/timer/fsl,imxgpt.txt
> > index 9809b11..4e9fa16 100644
> > --- a/Documentation/devicetree/bindings/timer/fsl,imxgpt.txt
> > +++ b/Documentation/devicetree/bindings/timer/fsl,imxgpt.txt
> > @@ -2,17 +2,21 @@ Freescale i.MX General Purpose Timer (GPT)
> >
> >  Required properties:
> >
> > -- compatible : should be "fsl,<soc>-gpt"
> > -- reg : Specifies base physical address and size of the registers.
> > -- interrupts : A list of 4 interrupts; one per timer channel.
> > -- clocks : The clocks provided by the SoC to drive the timer.
> > +- compatible : should be "fsl,<soc>-gpt".
> 
> This should enumerate valid <soc> values.

Agree, I list all the available compatible strings in GPT driver here in V2 patch.

> 
> > +- reg : specifies base physical address and size of the registers.
> > +- interrupts : should be the clock event device interrupt.
> > +- clocks : the clocks provided by the SoC to drive the timer, must contain
> > +           an entry for each entry in clock-names.
> > +- clock-names : must include an "per" or "osc_per" entry, and "ipg" entry
> > +                is optional according to SoC design.
> 
> Need to define the order. Ideally the optional clock should be last, but that's
> not what the example has.

Current GPT driver does NOT have the order requirement since it all gets clk by name, but
I think specifying the order is better, I update it in V2 patch.

> 
> >
> >  Example:
> >
> > -gpt1: timer@10003000 {
> > -	compatible = "fsl,imx27-gpt", "fsl,imx1-gpt";
> > -	reg = <0x10003000 0x1000>;
> > -	interrupts = <26>;
> > -	clocks = <&clks 46>, <&clks 61>;
> > +gpt: gpt@2098000 {
> 
> timer@...
> 
> > +	compatible = "fsl,imx6sx-gpt", "fsl,imx31-gpt";
> 
> You haven't documented "fsl,imx31-gpt" is a valid fallback. Is the old example
> not still valid for imx27?
> 
> > +	reg = <0x02098000 0x4000>;
> 
> Using a size > 4KB just wastes virtual space which is valuable on 32-bit systems
> with >= 1GB RAM.

I forgot that old example is still valid, so I will just use old example here, but the old
example of i.MX27 GPT already NOT match with latest i.MX27 dtsi GPT node, I update
it with latest GPT node in i.MX27 dtsi in V2 patch, please help review it, thanks.

Anson. 

> 
> > +	interrupts = <GIC_SPI 55 IRQ_TYPE_LEVEL_HIGH>;
> > +	clocks = <&clks IMX6SX_CLK_GPT_BUS>,
> > +		 <&clks IMX6SX_CLK_GPT_3M>;
> >  	clock-names = "ipg", "per";
> >  };
> > --
> > 2.7.4
> >