From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chanwoo Choi Subject: Re: [PATCH v2 10/19] PM / devfreq: tegra: Drop primary interrupt handler Date: Tue, 16 Apr 2019 14:56:54 +0900 Message-ID: <93574885-d695-2288-a4c6-2b845ad8daaf@samsung.com> References: <20190415145505.18397-1-digetx@gmail.com> <20190415145505.18397-11-digetx@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190415145505.18397-11-digetx@gmail.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Dmitry Osipenko , Thierry Reding , Jonathan Hunter , MyungJoo Ham , Kyungmin Park , Tomeu Vizoso Cc: linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org List-Id: linux-tegra@vger.kernel.org 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 > --- > 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