Re: [PATCH RFC 05/15] ims-msi: Add mask/unmask routines

Dey, Megha
2020-05-04T00:16:22Z

Hi Thomas,

On 4/25/2020 2:49 PM, Thomas Gleixner wrote:
> Dave Jiang <dave.jiang@intel.com> writes:
>>
>> +static u32 __dev_ims_desc_mask_irq(struct msi_desc *desc, u32 flag)
>
> ...mask_irq()? This is doing both mask and unmask depending on the
> availability of the ops callbacks.

yes, should have called it __dev_ims_desc_mask_unmask_irq perhaps.
>
>> +{
>> + u32 mask_bits = desc->platform.masked;
>> + const struct platform_msi_ops *ops;
>> +
>> + ops = desc->platform.msi_priv_data->ops;
>> + if (!ops)
>> + return 0;
>> +
>> + if (flag) {
>
> flag? Darn, this has a clear boolean meaning of mask or unmask and 'u32
> flag' is the most natural and obvious self explaining expression for
> this, right?

will change it a more meaningful name next time around ..
>
>> + if (ops->irq_mask)
>> + mask_bits = ops->irq_mask(desc);
>> + } else {
>> + if (ops->irq_unmask)
>> + mask_bits = ops->irq_unmask(desc);
>> + }
>> +
>> + return mask_bits;
>
> What's mask_bits? This is about _ONE_ IMS interrupt. Can it have
> multiple mask bits and if so then the explanation which I decoded by
> crystal ball probably looks like this:
>
> Bit 0: Don't know whether it's masked
> Bit 1: Perhaps it's masked
> Bit 2: Probably it's masked
> Bit 3: Mostly masked
> ...
> Bit 31: Fully masked
>
> Or something like that. Makes a lot of sense in a XKCD cartoon at least.
>

After a close look, we can simply do away with this mask_bits. Looks
like a crystal ball will not be required next time around after all.

>> +}
>> +
>> +/**
>> + * dev_ims_mask_irq - Generic irq chip callback to mask IMS interrupts
>> + * @data: pointer to irqdata associated to that interrupt
>> + */
>> +static void dev_ims_mask_irq(struct irq_data *data)
>> +{
>> + struct msi_desc *desc = irq_data_get_msi_desc(data);
>> +
>> + desc->platform.masked = __dev_ims_desc_mask_irq(desc, 1);
>
> The purpose of this masked information is?

serves no purpose, borrowed this concept from the PCI-msi code but is
just junk here. Will be removed next time around.

>
> Thanks,
>
> tglx
>