Re: [PATCH v2 1/4] ACPI / watchdog: Add support for WDAT hardware watchdog

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On 09/20/2016 06:50 AM, Mika Westerberg wrote:
On Tue, Sep 20, 2016 at 06:37:23AM -0700, Guenter Roeck wrote:
+	for (i = 0; i < tbl->entries; i++) {
+		const struct acpi_generic_address *gas;
+		struct wdat_instruction *instr;
+		struct list_head *instructions;
+		unsigned int action;
+		struct resource r;
+		int j;
+
+		action = entries[i].action;
+		if (action >= MAX_WDAT_ACTIONS) {
+			dev_dbg(&pdev->dev, "Skipping unknown action: %u\n",
+				action);
+			continue;
+		}
+
+		instr = devm_kzalloc(&pdev->dev, sizeof(*instr), GFP_KERNEL);
+		if (!instr)
+			return -ENOMEM;
+
+		INIT_LIST_HEAD(&instr->node);
+		instr->entry = entries[i];
+
+		gas = &entries[i].register_region;
+
+		memset(&r, 0, sizeof(r));
+		r.start = gas->address;
+		r.end = r.start + gas->access_width;
+		if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
+			r.flags = IORESOURCE_MEM;
+		} else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
+			r.flags = IORESOURCE_IO;
+		} else {
+			dev_dbg(&pdev->dev, "Unsupported address space: %d\n",
+				gas->space_id);
+			continue;
+		}
+
+		/* Find the matching resource */
+		for (j = 0; j < pdev->num_resources; j++) {
+			res = &pdev->resource[j];
+			if (resource_contains(res, &r)) {
+				instr->reg = regs[j] + r.start - res->start;
+				break;
+			}
+		}
+
+		if (!instr->reg) {
+			dev_err(&pdev->dev, "I/O resource not found\n");
+			return -EINVAL;
+		}
+
I must be missing something here. What is happening with instr ?

Instr contains the actual instruction from WDAT table. There can be
many.

+		instructions = wdat->instructions[action];

This will be NULL first time so...

+		if (!instructions) {
+			instructions = devm_kzalloc(&pdev->dev,
+					sizeof(*instructions), GFP_KERNEL);
+			if (!instructions)
+				return -ENOMEM;
+
+			INIT_LIST_HEAD(instructions);
+			wdat->instructions[action] = instructions;

... and I don't really see how wdat->instructions[action] contains anything but
a zero filled array. Confused :-(.

...we allocate entry for that here. Next time it will not be NULL for
that action.


+		}
+
+		list_add_tail(&instr->node, instructions);

Then we append each instr to the list for this action.

Hope this clarifies :)

Yes, I somehow didn't see that last line. Too early in the morning,
not enough coffee.

Thanks,
Guenter

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