Re: [PATCH v3 06/10] mtd: brcmstb_nand: add SoC-specific support

nick
2015-05-06T21:00:09Z

On 2015-05-06 04:49 PM, Brian Norris wrote:
> On Wed, May 06, 2015 at 09:12:43PM +0200, Arnd Bergmann wrote:
>> On Wednesday 06 May 2015 10:59:50 Brian Norris wrote:
>>> + /*
>>> + * Some SoCs integrate this controller (e.g., its interrupt bits) in
>>> + * interesting ways
>>> + */
>>> + if (of_property_read_bool(dn, "brcm,nand-soc")) {
>>> + struct device_node *soc_dn;
>>> +
>>> + soc_dn = of_parse_phandle(dn, "brcm,nand-soc", 0);
>>> + if (!soc_dn)
>>> + return -ENODEV;
>>> +
>>> + ctrl->soc = devm_brcmnand_probe_soc(dev, soc_dn);
>>> + if (!ctrl->soc) {
>>> + dev_err(dev, "could not probe SoC data\n");
>>> + of_node_put(soc_dn);
>>> + return -ENODEV;
>>> + }
>>> +
>>> + ret = devm_request_irq(dev, ctrl->irq, brcmnand_irq, 0,
>>> + DRV_NAME, ctrl);
>>> +
>>> + /* Enable interrupt */
>>> + ctrl->soc->ctlrdy_set_enabled(ctrl->soc, true);
>>> +
>>> + of_node_put(soc_dn);
>>> + } else {
>>> + /* Use standard interrupt infrastructure */
>>> + ret = devm_request_irq(dev, ctrl->irq, brcmnand_ctlrdy_irq, 0,
>>> + DRV_NAME, ctrl);
>>> + }
>>>
>>
>> It looks to me like this should be handled as a nested irqchip, so the node
>> you look up gets used as the "interrupt-parent" instead, making the behavior
>> of this SoC transparent to the nand driver.
>
> You snipped the rest of the patch, which involves more than just IRQ
> handling. The same registers touch both interrupts and data bus endian
> configuration, so it can't possibly be done transparently to the NAND
> driver.
>
>> We recently merged nested irqdomain support as well, which might help here,
>> or might not be needed.
>
> I'm not familiar with nested irqdomains. Do they address anything like
> the above problem?
>
> Brian
>
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> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
>
Brian,
I don't known about them myself :). However always check the Documentation folder of the kernel
root for things like this. Further more I already checked there and it appears there is a file
explaining the basics entitled, IRQ-domain.txt.
Hope this helps,
Nick

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