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SubjectRe: [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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