Re: [PATCH 02/14] dmaengine: dma-jz4780: Separate chan/ctrl registers

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Le mer. 11 juil. 2018 à 14:16, Vinod <vkoul@xxxxxxxxxx> a écrit :
On 10-07-18, 17:36, Paul Cercueil wrote:

 > >  @@ -3,7 +3,8 @@
 > >   Required properties:
 > >
 > >   - compatible: Should be "ingenic,jz4780-dma"
> > -- reg: Should contain the DMA controller registers location and
 > > length.
 > >  +- reg: Should contain the DMA channel registers location and
 > > length, followed
 > >  +  by the DMA controller registers location and length.
> > - interrupts: Should contain the interrupt specifier of the DMA
 > > controller.
 > >   - interrupt-parent: Should be the phandle of the interrupt
 > > controller that
 > >   - clocks: Should contain a clock specifier for the JZ4780 PDMA
 > > clock.
 > >  @@ -22,7 +23,8 @@ Example:
 > >
 > >   dma: dma@13420000 {
 > >   	compatible = "ingenic,jz4780-dma";
 > >  -	reg = <0x13420000 0x10000>;
 > >  +	reg = <0x13420000 0x400
 > >  +	       0x13421000 0x40>;
 >
 > Second should be optional or we break platform which may not have
 > updated DT..

 See comment below.

 > >  -	jzdma->base = devm_ioremap_resource(dev, res);
 > >  -	if (IS_ERR(jzdma->base))
 > >  -		return PTR_ERR(jzdma->base);
 > >  +	jzdma->chn_base = devm_ioremap_resource(dev, res);
 > >  +	if (IS_ERR(jzdma->chn_base))
 > >  +		return PTR_ERR(jzdma->chn_base);
 > >  +
 > >  +	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 > >  +	if (!res) {
 > >  +		dev_err(dev, "failed to get I/O memory\n");
 > >  +		return -EINVAL;
 > >  +	}
 >
> okay and this breaks if you happen to get probed on older DT. I think DT > is treated as ABI so you need to continue support older method while
 > finding if DT has split resources

See my response to PrasannaKumar. All the Ingenic-based boards do compile the devicetree within the kernel, so I think it's still fine to add breaking changes. I'll wait on @Rob to give his point of view on this, though.

(It's not something hard to change, but I'd like to know what's the policy
 in that case. I have other DT-breaking patches to submit)

The policy is that DT is an ABI and should not break :)

Who maintains Ingenic arch. MAINTAINERS doesn't tell me.

Unofficially that would be me :)

Otherwise that would be the MIPS maintainers, Ralf and Paul (Burton).

--
~Vinod

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