Re: [PATCH v4 10/11] drivers: perf: hisi: Handle counter overflow IRQ in MN PMU

From: Anurup M
Date: Thu Feb 23 2017 - 22:05:09 EST

Sorry for delay in reply.

On Tuesday 21 February 2017 05:33 PM, Mark Rutland wrote:
On Tue, Feb 21, 2017 at 05:19:58PM +0530, Anurup M wrote:
On Monday 20 February 2017 04:59 PM, Mark Rutland wrote:
On Sun, Feb 19, 2017 at 01:51:22PM -0500, Anurup M wrote:
+ /* Clear the IRQ status flag */
+ hisi_djtag_writereg(module_id, MN1_BANK_SELECT,
+ MN1_INTC_REG_OFF, (1 << bit_pos), client);
+ /* Get the corresponding event struct */
+ event = mn_pmu->hw_perf_events[bit_pos];
+ if (!event)
+ continue;
Do we expect to take interrupts for an event which does not exist?
Here I ignore if the event does not exist. I have seen it is handled
in arm_pmu and other reference
implementations to ignore if there is no event.
The event is cleared in .del. So if .del is called before the IRQ
handler, this check is required right?
Please comment.
If there's a particular case whre we'd see the overflow bit set for an
event, please add a comment describing that case here.


Sure. I will do that.

+static int hisi_mn_init_irqs_fdt(struct device *dev,
+ struct hisi_pmu *mn_pmu)
+ struct hisi_mn_data *mn_data = mn_pmu->hwmod_data;
+ struct hisi_djtag_client *client = mn_data->client;
+ int irq = -1, num_irqs, i;
+ num_irqs = of_irq_count(dev->of_node);
Surely we expect a specific number of interrupts?

+ for (i = 0; i < num_irqs; i++) {
+ irq = of_irq_get(dev->of_node, i);
+ if (irq < 0)
+ dev_info(dev, "No IRQ resource!\n");
+ }
Why are we throwing these away?

+ if (irq < 0)
+ return 0;
+ /* The last entry in the IRQ list to be chosen
+ * This is as per mbigen-v2 IRQ mapping
+ */
+ return hisi_mn_init_irq(irq, mn_pmu, client);
I don't understand this comment.

Why do we only use the list IRQ?

What does this have to do with the mbigen?

No ordering requirement was described in the DT binding.
There is a defect in the mbigen hardware to handle the IRQ mapping
for MN.
Due to this the IRQ property
of MN is made as a list and we read all IRQs and use only the last one.
I shall mention it in the comment and also add note in the DT bindings.
You'll need to elaborate on that a bit further; I don't understand.

If the interrupts aren't usable, there's arguably not much point listing
them in the DT.

Regardless, the order of the list *must* be specified in the DT binding.

I'm sorry for creating this confusion. It was a wrong workaround due to my misunderstanding of the
IRQ mapping.
The MN will use a single IRQ for overflow in HiP07. I shall update it and resend.
But in HiP05/06 there is no support for this IRQ, So I shall modify to use polling when IRQ is not available.