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Message-ID: <9726a08f-266e-2949-8141-3a726ffd2795@quicinc.com>
Date: Thu, 8 Dec 2022 20:32:57 +0530
From: Akhil P Oommen <quic_akhilpo@...cinc.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
CC: freedreno <freedreno@...ts.freedesktop.org>,
<dri-devel@...ts.freedesktop.org>, <linux-arm-msm@...r.kernel.org>,
Rob Clark <robdclark@...il.com>,
Bjorn Andersson <andersson@...nel.org>,
Stephen Boyd <swboyd@...omium.org>,
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Philipp Zabel <p.zabel@...gutronix.de>,
Douglas Anderson <dianders@...omium.org>,
<krzysztof.kozlowski@...aro.org>, Andy Gross <agross@...nel.org>,
Konrad Dybcio <konrad.dybcio@...ainline.org>,
Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>, <linux-clk@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 3/6] clk: qcom: gdsc: Add a reset op to poll gdsc
collapse
On 12/7/2022 9:15 PM, Ulf Hansson wrote:
> On Wed, 5 Oct 2022 at 11:08, Akhil P Oommen <quic_akhilpo@...cinc.com> wrote:
>> Add a reset op compatible function to poll for gdsc collapse. This is
>> required because:
>> 1. We don't wait for it to turn OFF at hardware for VOTABLE GDSCs.
>> 2. There is no way for client drivers (eg. gpu driver) to do
>> put-with-wait for these gdscs which is required in some scenarios
>> (eg. GPU recovery).
> What puzzles me a bit, who is the typical consumer of the reset.
>
> I looked at patch4 and tried to figure it out, but let's discuss that
> in that thread instead. Some more comments, see below.
https://patchwork.freedesktop.org/patch/498397/
gpu driver side changes are already merged in upstream. We call this interface during a GPU recovery which is supposed to be a rare event.
>
>> Signed-off-by: Akhil P Oommen <quic_akhilpo@...cinc.com>
>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
>> ---
>>
>> Changes in v7:
>> - Update commit message (Bjorn)
>>
>> Changes in v2:
>> - Minor update to function prototype
>>
>> drivers/clk/qcom/gdsc.c | 23 +++++++++++++++++++----
>> drivers/clk/qcom/gdsc.h | 7 +++++++
>> 2 files changed, 26 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
>> index 7cf5e13..ccef742 100644
>> --- a/drivers/clk/qcom/gdsc.c
>> +++ b/drivers/clk/qcom/gdsc.c
>> @@ -17,6 +17,7 @@
>> #include <linux/reset-controller.h>
>> #include <linux/slab.h>
>> #include "gdsc.h"
>> +#include "reset.h"
>>
>> #define PWR_ON_MASK BIT(31)
>> #define EN_REST_WAIT_MASK GENMASK_ULL(23, 20)
>> @@ -116,7 +117,8 @@ static int gdsc_hwctrl(struct gdsc *sc, bool en)
>> return regmap_update_bits(sc->regmap, sc->gdscr, HW_CONTROL_MASK, val);
>> }
>>
>> -static int gdsc_poll_status(struct gdsc *sc, enum gdsc_status status)
>> +static int gdsc_poll_status(struct gdsc *sc, enum gdsc_status status,
>> + s64 timeout_us, unsigned int interval_ms)
>> {
>> ktime_t start;
>>
>> @@ -124,7 +126,9 @@ 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);
>> + if (interval_ms)
>> + msleep(interval_ms);
>> + } while (ktime_us_delta(ktime_get(), start) < timeout_us);
> Rather than continue to open code this polling loop, would it not make
> sense to convert the code into using readx_poll_timeout() (or some of
> its friends).
I was going for a minimal code churn to get this mainlined easily. I like the idea, perhaps we can have a refactor patch if there is consensus.
-Akhil.
>
> Down the road, this leads to that the msleep() above should become
> usleep_range() instead, which seems more correct to me.
>
>> if (gdsc_check_status(sc, status))
>> return 0;
>> @@ -189,7 +193,7 @@ static int gdsc_toggle_logic(struct gdsc *sc, enum gdsc_status status)
>> udelay(1);
>> }
>>
>> - ret = gdsc_poll_status(sc, status);
>> + ret = gdsc_poll_status(sc, status, TIMEOUT_US, 0);
>> WARN(ret, "%s status stuck at 'o%s'", sc->pd.name, status ? "ff" : "n");
>>
>> if (!ret && status == GDSC_OFF && sc->rsupply) {
>> @@ -360,7 +364,7 @@ static int _gdsc_disable(struct gdsc *sc)
>> */
>> udelay(1);
>>
>> - ret = gdsc_poll_status(sc, GDSC_ON);
>> + ret = gdsc_poll_status(sc, GDSC_ON, TIMEOUT_US, 0);
>> if (ret)
>> return ret;
>> }
>> @@ -608,3 +612,14 @@ int gdsc_gx_do_nothing_enable(struct generic_pm_domain *domain)
>> return 0;
>> }
>> EXPORT_SYMBOL_GPL(gdsc_gx_do_nothing_enable);
>> +
>> +int gdsc_wait_for_collapse(void *priv)
>> +{
>> + struct gdsc *sc = priv;
>> + int ret;
>> +
>> + ret = gdsc_poll_status(sc, GDSC_OFF, 500000, 5);
>> + WARN(ret, "%s status stuck at 'on'", sc->pd.name);
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(gdsc_wait_for_collapse);
>> diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
>> index 981a12c..5395f69 100644
>> --- a/drivers/clk/qcom/gdsc.h
>> +++ b/drivers/clk/qcom/gdsc.h
>> @@ -12,6 +12,7 @@
>> struct regmap;
>> struct regulator;
>> struct reset_controller_dev;
>> +struct qcom_reset_map;
>>
>> /**
>> * struct gdsc - Globally Distributed Switch Controller
>> @@ -88,6 +89,7 @@ int gdsc_register(struct gdsc_desc *desc, struct reset_controller_dev *,
>> struct regmap *);
>> void gdsc_unregister(struct gdsc_desc *desc);
>> int gdsc_gx_do_nothing_enable(struct generic_pm_domain *domain);
>> +int gdsc_wait_for_collapse(void *priv);
>> #else
>> static inline int gdsc_register(struct gdsc_desc *desc,
>> struct reset_controller_dev *rcdev,
>> @@ -97,5 +99,10 @@ static inline int gdsc_register(struct gdsc_desc *desc,
>> }
>>
>> static inline void gdsc_unregister(struct gdsc_desc *desc) {};
>> +
>> +static int gdsc_wait_for_collapse(void *priv)
>> +{
>> + return -ENOSYS;
>> +}
>> #endif /* CONFIG_QCOM_GDSC */
>> #endif /* __QCOM_GDSC_H__ */
> Kind regards
> Uffe
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