On Wed, 5 Oct 2022 at 11:08, Akhil P Oommen <quic_akhilpo@xxxxxxxxxxx> 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.
>
> Signed-off-by: Akhil P Oommen <quic_akhilpo@xxxxxxxxxxx>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> ---
>
> 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).
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
