Re: [RESEND PATCHv4 1/1] drivers/amba: add reset control to amba bus probe

From: Dinh Nguyen
Date: Mon Aug 26 2019 - 11:27:19 EST


Hi Philipp,

On 8/26/19 3:57 AM, Philipp Zabel wrote:
> Hi Dinh, Linus,
>
> On Fri, 2019-08-23 at 10:42 -0500, Dinh Nguyen wrote:
>>
>> On 8/23/19 4:19 AM, Linus Walleij wrote:
>>> On Tue, Aug 20, 2019 at 4:58 PM Dinh Nguyen <dinguyen@xxxxxxxxxx> wrote:
>>>
>>>> @@ -401,6 +402,26 @@ static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
>>>> ret = amba_get_enable_pclk(dev);
>>>> if (ret == 0) {
>>>> u32 pid, cid;
>>>> + int count;
>>>> + struct reset_control *rstc;
>>>> +
>>>> + /*
>>>> + * Find reset control(s) of the amba bus and de-assert them.
>>>> + */
>>>> + count = reset_control_get_count(&dev->dev);
>
> The reset_control_get_count() inline stub returns -ENOENT, so the
> compiler can throw away the complete loop.
>
>>>> + while (count > 0) {
>>>> + rstc = of_reset_control_get_shared_by_index(dev->dev.of_node, count - 1);
>
> Since resets are looked up with of_reset_control_get, I'd use
> of_reset_control_get_count() above for consistency. But see below:
>

reset_control_get_count() ultimately calls of_reset_control_get_count()
and it looks like of_reset_control_get_count() is not exported.

>>>> + if (IS_ERR(rstc)) {
>>>> + if (PTR_ERR(rstc) == -EPROBE_DEFER)
>>>> + ret = -EPROBE_DEFER;
>>>> + else
>>>> + dev_err(&dev->dev, "Can't get amba reset!\n");
>>>> + break;
>>>> + }
>>>> + reset_control_deassert(rstc);
>>>> + reset_control_put(rstc);
>>>> + count--;
>>>> + }
>
> It looks like the order of deassertions is irrelevant. If so,
> You can use of_reset_control_array_get() to simplify this:
>
> + rstc = of_reset_control_array_get_optional_shared(dev->dev.of_node);
> + if (IS_ERR(rstc)) {
> + if (PTR_ERR(rstc) != -EPROBE_DEFER)
> + dev_err(&dev->dev, "Can't get amba reset!\n");
> + return PTR_ERR(rstc);
> + }
> + reset_control_deassert(rstc);
> + reset_control_put(rstc);
>

Thanks for the review! I'll post v5 shortly.

Dinh