linux-kernel - Re: [PATCH 2/9] clk: qcom: gdsc: Add configurable poll timeout

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Date:   Thu, 17 Nov 2022 10:23:01 +0100
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Abel Vesa <abel.vesa@...aro.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Mike Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH 2/9] clk: qcom: gdsc: Add configurable poll timeout



On 17/11/2022 09:05, Abel Vesa wrote:
> On 22-11-16 12:19:09, Konrad Dybcio wrote:
>>
>>
>> On 16/11/2022 11:47, Abel Vesa wrote:
>>> Depending on the platform, the poll timeout delay might be different,
>>> so allow the platform specific drivers to specify their own values.
>>>
>>> Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
>>> ---
>>>    drivers/clk/qcom/gdsc.c | 5 ++++-
>>>    drivers/clk/qcom/gdsc.h | 1 +
>>>    2 files changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
>>> index 0f21a8a767ac..3753f3ef7241 100644
>>> --- a/drivers/clk/qcom/gdsc.c
>>> +++ b/drivers/clk/qcom/gdsc.c
>>> @@ -107,7 +107,7 @@ static int gdsc_poll_status(struct gdsc *sc, enum gdsc_status status)
>>>    	do {
>>>    		if (gdsc_check_status(sc, status))
>>>    			return 0;
>>> -	} while (ktime_us_delta(ktime_get(), start) < TIMEOUT_US);
>>> +	} while (ktime_us_delta(ktime_get(), start) < sc->poll_timeout);
>> What about the second usage of TIMEOUT_US (in gdsc_toggle_logic)? Is it fine
>> for that to be the default value?
> 
> The usleep you mention is not really for polling the state.
> So I think it should stay as is. Who knows, maybe in the future we will
> need to have the configurable as well, but as a toggle delay rather than
> a status poll timeout.
> 
> I added this configurable poll timeout just because I saw that
> downstream, each driver has different values. And it kind of makes sense,
> because the state machine inside the GDSC might be different between
> platforms, and so, it might take different time to reach a certain on/off
> state.
> 
> Thanks,
> Abel
Okay, thanks for explaining

Reviewed-by: Konrad Dybcio <konrad.dybcio@...aro.org>

Konrad
> 
>>
>>
>> Konrad
>>>    	if (gdsc_check_status(sc, status))
>>>    		return 0;
>>> @@ -454,6 +454,9 @@ static int gdsc_init(struct gdsc *sc)
>>>    	if (ret)
>>>    		goto err_disable_supply;
>>> +	if (!sc->poll_timeout)
>>> +		sc->poll_timeout = 500;
>>> +
>>>    	return 0;
>>>    err_disable_supply:
>>> diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
>>> index 803512688336..9a1e1fb3d12f 100644
>>> --- a/drivers/clk/qcom/gdsc.h
>>> +++ b/drivers/clk/qcom/gdsc.h
>>> @@ -36,6 +36,7 @@ struct gdsc {
>>>    	struct generic_pm_domain	*parent;
>>>    	struct regmap			*regmap;
>>>    	unsigned int			gdscr;
>>> +	unsigned int			poll_timeout;
>>>    	unsigned int			collapse_ctrl;
>>>    	unsigned int			collapse_mask;
>>>    	unsigned int			gds_hw_ctrl;