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

[Guenter Roeck]

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