Re: [PATCH v4 04/24] PM / devfreq: tegra30: Drop write-barrier

Chanwoo Choi
2019-07-16T11:51:19Z

Hi Dmitry,

On 19. 7. 8. 오전 7:32, Dmitry Osipenko wrote:
> There is no need in a write-barrier now, given that interrupt masking is
> handled by CPU's GIC now. Hence we know exactly that interrupt won't fire
> after stopping the devfreq's governor. In other cases we don't care about
> potential buffering of the writes to hardware and thus there is no need to
> stall CPU.
>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> drivers/devfreq/tegra30-devfreq.c | 14 --------------
> 1 file changed, 14 deletions(-)
>
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 5e606ae3f238..4be7858c33bc 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -230,12 +230,6 @@ static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
> ACTMON_DEV_LOWER_WMARK);
> }
>
> -static void actmon_write_barrier(struct tegra_devfreq *tegra)
> -{
> - /* ensure the update has reached the ACTMON */
> - readl(tegra->regs + ACTMON_GLB_STATUS);
> -}
> -
> static void actmon_isr_device(struct tegra_devfreq *tegra,
> struct tegra_devfreq_device *dev)
> {
> @@ -287,8 +281,6 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
> device_writel(dev, dev_ctrl, ACTMON_DEV_CTRL);
>
> device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS);
> -
> - actmon_write_barrier(tegra);
> }
>
> static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra,
> @@ -376,8 +368,6 @@ static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
> tegra_devfreq_update_wmark(tegra, dev);
> }
>
> - actmon_write_barrier(tegra);
> -
> return NOTIFY_OK;
> }
>
> @@ -423,8 +413,6 @@ static void tegra_actmon_start(struct tegra_devfreq *tegra)
> for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
> tegra_actmon_configure_device(tegra, &tegra->devices[i]);
>
> - actmon_write_barrier(tegra);
> -
> enable_irq(tegra->irq);
> }
>
> @@ -439,8 +427,6 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
> device_writel(&tegra->devices[i], ACTMON_INTR_STATUS_CLEAR,
> ACTMON_DEV_INTR_STATUS);
> }
> -
> - actmon_write_barrier(tegra);
> }
>
> static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
>

Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>

--
Best Regards,
Chanwoo Choi
Samsung Electronics