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Date: Tue, 16 Apr 2019 14:56:54 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: Dmitry Osipenko <digetx@...il.com>,
Thierry Reding <thierry.reding@...il.com>,
Jonathan Hunter <jonathanh@...dia.com>,
MyungJoo Ham <myungjoo.ham@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc: linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 10/19] PM / devfreq: tegra: Drop primary interrupt
handler
Hi,
It looks good to me to drop the primary interrupt handler
but I have some comments. Please check it.
On 19. 4. 15. 오후 11:54, Dmitry Osipenko wrote:
> There is no real need in the primary interrupt handler, hence move
> everything to the secondary (threaded) handler. In a result locking
> is consistent now and there are no potential races with the interrupt
> handler because it is protected with the devfreq's mutex.
>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
> drivers/devfreq/tegra-devfreq.c | 61 ++++++++++++---------------------
> 1 file changed, 22 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c
> index 2a1464098200..69b557df5084 100644
> --- a/drivers/devfreq/tegra-devfreq.c
> +++ b/drivers/devfreq/tegra-devfreq.c
> @@ -144,7 +144,6 @@ static struct tegra_devfreq_device_config actmon_device_configs[] = {
> struct tegra_devfreq_device {
> const struct tegra_devfreq_device_config *config;
> void __iomem *regs;
> - spinlock_t lock;
>
> /* Average event count sampled in the last interrupt */
> u32 avg_count;
> @@ -249,11 +248,8 @@ static void actmon_write_barrier(struct tegra_devfreq *tegra)
> static void actmon_isr_device(struct tegra_devfreq *tegra,
> struct tegra_devfreq_device *dev)
> {
> - unsigned long flags;
> u32 intr_status, dev_ctrl;
>
> - spin_lock_irqsave(&dev->lock, flags);
> -
> dev->avg_count = device_readl(dev, ACTMON_DEV_AVG_COUNT);
> tegra_devfreq_update_avg_wmark(tegra, dev);
>
> @@ -302,26 +298,6 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
> device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS);
>
> actmon_write_barrier(tegra);
> -
> - spin_unlock_irqrestore(&dev->lock, flags);
> -}
> -
> -static irqreturn_t actmon_isr(int irq, void *data)
> -{
> - struct tegra_devfreq *tegra = data;
> - bool handled = false;
> - unsigned int i;
> - u32 val;
> -
> - val = actmon_readl(tegra, ACTMON_GLB_STATUS);
> - for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
> - if (val & tegra->devices[i].config->irq_mask) {
> - actmon_isr_device(tegra, tegra->devices + i);
> - handled = true;
> - }
> - }
> -
> - return handled ? IRQ_WAKE_THREAD : IRQ_NONE;
> }
>
> static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra,
> @@ -348,35 +324,46 @@ static void actmon_update_target(struct tegra_devfreq *tegra,
> unsigned long cpu_freq = 0;
> unsigned long static_cpu_emc_freq = 0;
> unsigned int avg_sustain_coef;
> - unsigned long flags;
> + u32 avg_count;
>
> if (dev->config->avg_dependency_threshold) {
> cpu_freq = cpufreq_get(0);
> static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpu_freq);
> }
>
> - spin_lock_irqsave(&dev->lock, flags);
> -
> - dev->target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD;
> + avg_count = dev->avg_count;
> + dev->target_freq = avg_count / ACTMON_SAMPLING_PERIOD;
Actually, this change is not related to this patch.
Please keep the original code.
> avg_sustain_coef = 100 * 100 / dev->config->boost_up_threshold;
> dev->target_freq = do_percent(dev->target_freq, avg_sustain_coef);
> dev->target_freq += dev->boost_freq;
>
> - if (dev->avg_count >= dev->config->avg_dependency_threshold)
> + if (avg_count >= dev->config->avg_dependency_threshold)
ditto.
> dev->target_freq = max(dev->target_freq, static_cpu_emc_freq);
> -
> - spin_unlock_irqrestore(&dev->lock, flags);
> }
>
> static irqreturn_t actmon_thread_isr(int irq, void *data)
> {
> struct tegra_devfreq *tegra = data;
> + bool handled = false;
> + unsigned int i;
> + u32 val;
>
> mutex_lock(&tegra->devfreq->lock);
> - update_devfreq(tegra->devfreq);
> +
> + val = actmon_readl(tegra, ACTMON_GLB_STATUS);
> + for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
> + if (val & tegra->devices[i].config->irq_mask) {
> + actmon_isr_device(tegra, tegra->devices + i);
> + handled = true;
> + }
> + }
> +
> + if (handled)
> + update_devfreq(tegra->devfreq);
> +
> mutex_unlock(&tegra->devfreq->lock);
>
> - return IRQ_HANDLED;
> + return handled ? IRQ_HANDLED : IRQ_NONE;
> }
>
> static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
> @@ -386,7 +373,6 @@ static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
> struct tegra_devfreq *tegra;
> struct tegra_devfreq_device *dev;
> unsigned int i;
> - unsigned long flags;
>
> if (action != POST_RATE_CHANGE)
> return NOTIFY_OK;
> @@ -398,9 +384,7 @@ static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
When I review this patch, I have a question
about why tegra_actmon_rate_notify_cb is needed.
tegra_actmon_rate_notify_cb() do something
when the clock rate of emc_clock is changed.
I think that 'emc_clock' is changed by this driver.
It means that the this driver can catch the change timing
of emc_clock rate without notifier.
IMO, it is possible to call tegra_devfreq_update_wmark()
directly without clock notifier before calling
'clk_set_min_rate()/clk_set_rate()' in the tegra_devfreq_target().
With clock notifier, it cannot restore something for
tegra_devfreq_update_wmark(tegra, dev) when failed to
set the rate of emc_clk by 'clk_set_min_rate()/clk_set_rate()'.
> for (i = 0; i < ARRAY_SIZE(tegra->devices); i++) {
> dev = &tegra->devices[i];
>
> - spin_lock_irqsave(&dev->lock, flags);
> tegra_devfreq_update_wmark(tegra, dev);
> - spin_unlock_irqrestore(&dev->lock, flags);
> }
>
> actmon_write_barrier(tegra);
> @@ -668,7 +652,6 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
> dev = tegra->devices + i;
> dev->config = actmon_device_configs + i;
> dev->regs = tegra->regs + dev->config->offset;
> - spin_lock_init(&dev->lock);
>
> tegra_actmon_configure_device(tegra, dev);
> }
> @@ -696,8 +679,8 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
> return err;
> }
>
> - err = devm_request_threaded_irq(&pdev->dev, irq, actmon_isr,
> - actmon_thread_isr, IRQF_SHARED,
> + err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
> + actmon_thread_isr, IRQF_ONESHOT,
> "tegra-devfreq", tegra);
> if (err) {
> dev_err(&pdev->dev, "Interrupt request failed\n");
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
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