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

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Hi Thomas,

On 4/25/2020 2:49 PM, Thomas Gleixner wrote:
Dave Jiang <dave.jiang@xxxxxxxxx> 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




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