Re: [PATCH v4 14/21] PM / devfreq: rockchip-dfi: Prepare for multiple users
From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
Date: 2023-05-16 16:17:32
Also in:
linux-rockchip
On Fri, 5 May 2023 13:38:49 +0200 Sascha Hauer [off-list ref] wrote:
When adding perf support later the DFI must be enabled when either of devfreq-event or perf is active. Prepare for that by adding a usage counter for the DFI. Also move enabling and disabling of the clock away from the devfreq-event specific functions to which the perf specific part won't have access. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
The clock code is IIRC refcounted anyway and I think has appropriate locks, so you code just enable / disable that in both paths. Probably not that helpful though given you still need to refcount to protect the register writes. So this looks fine to me. Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
quoted hunk ↗ jump to hunk
--- drivers/devfreq/event/rockchip-dfi.c | 57 +++++++++++++++++++--------- 1 file changed, 40 insertions(+), 17 deletions(-)diff --git a/drivers/devfreq/event/rockchip-dfi.c b/drivers/devfreq/event/rockchip-dfi.c index c0b7b1e9805e9..eae010644935a 100644 --- a/drivers/devfreq/event/rockchip-dfi.c +++ b/drivers/devfreq/event/rockchip-dfi.c@@ -69,13 +69,28 @@ struct rockchip_dfi { void __iomem *regs; struct regmap *regmap_pmu; struct clk *clk; + int usecount; + struct mutex mutex; u32 ddr_type; unsigned int channel_mask; }; -static void rockchip_dfi_start_hardware_counter(struct rockchip_dfi *dfi) +static int rockchip_dfi_enable(struct rockchip_dfi *dfi) { void __iomem *dfi_regs = dfi->regs; + int ret = 0; + + mutex_lock(&dfi->mutex); + + dfi->usecount++; + if (dfi->usecount > 1) + goto out; + + ret = clk_prepare_enable(dfi->clk); + if (ret) { + dev_err(&dfi->edev->dev, "failed to enable dfi clk: %d\n", ret); + goto out; + } /* clear DDRMON_CTRL setting */ writel_relaxed(HIWORD_UPDATE(0, 0xffff), dfi_regs + DDRMON_CTRL);@@ -99,14 +114,30 @@ static void rockchip_dfi_start_hardware_counter(struct rockchip_dfi *dfi) /* enable count, use software mode */ writel_relaxed(HIWORD_UPDATE(DDRMON_CTRL_SOFTWARE_EN, DDRMON_CTRL_SOFTWARE_EN), dfi_regs + DDRMON_CTRL); +out: + mutex_unlock(&dfi->mutex); + + return ret; } -static void rockchip_dfi_stop_hardware_counter(struct rockchip_dfi *dfi) +static void rockchip_dfi_disable(struct rockchip_dfi *dfi) { void __iomem *dfi_regs = dfi->regs; + mutex_lock(&dfi->mutex); + + dfi->usecount--; + + WARN_ON_ONCE(dfi->usecount < 0); + + if (dfi->usecount > 0) + goto out; + writel_relaxed(HIWORD_UPDATE(0, DDRMON_CTRL_SOFTWARE_EN), dfi_regs + DDRMON_CTRL); + clk_disable_unprepare(dfi->clk); +out: + mutex_unlock(&dfi->mutex); } static void rockchip_dfi_read_counters(struct rockchip_dfi *dfi, struct dmc_count *count)@@ -124,29 +155,20 @@ static void rockchip_dfi_read_counters(struct rockchip_dfi *dfi, struct dmc_coun } } -static int rockchip_dfi_disable(struct devfreq_event_dev *edev) +static int rockchip_dfi_event_disable(struct devfreq_event_dev *edev) { struct rockchip_dfi *dfi = devfreq_event_get_drvdata(edev); - rockchip_dfi_stop_hardware_counter(dfi); - clk_disable_unprepare(dfi->clk); + rockchip_dfi_disable(dfi);
Similar to below. Up to you on whether you prefer shorter code vs having the type of the parameter explicit in here.
return 0;
}
-static int rockchip_dfi_enable(struct devfreq_event_dev *edev)
+static int rockchip_dfi_event_enable(struct devfreq_event_dev *edev)
{
struct rockchip_dfi *dfi = devfreq_event_get_drvdata(edev);
- int ret;
-
- ret = clk_prepare_enable(dfi->clk);
- if (ret) {
- dev_err(&edev->dev, "failed to enable dfi clk: %d\n", ret);
- return ret;
- }
- rockchip_dfi_start_hardware_counter(dfi);
- return 0;
+ return rockchip_dfi_enable(dfi);No real point in local variable any more, so maybe return rockchip_dfi_enable(devfreq_event_get_drvdata(edev));
quoted hunk ↗ jump to hunk
} static int rockchip_dfi_set_event(struct devfreq_event_dev *edev)@@ -190,8 +212,8 @@ static int rockchip_dfi_get_event(struct devfreq_event_dev *edev, } static const struct devfreq_event_ops rockchip_dfi_ops = { - .disable = rockchip_dfi_disable, - .enable = rockchip_dfi_enable, + .disable = rockchip_dfi_event_disable, + .enable = rockchip_dfi_event_enable, .get_event = rockchip_dfi_get_event, .set_event = rockchip_dfi_set_event, };@@ -285,6 +307,7 @@ static int rockchip_dfi_probe(struct platform_device *pdev) return PTR_ERR(dfi->regmap_pmu); dfi->dev = dev; + mutex_init(&dfi->mutex); desc = &dfi->desc; desc->ops = &rockchip_dfi_ops;
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