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Message-id: <1413360550.25079.9.camel@AMDC1943>
Date: Wed, 15 Oct 2014 10:09:10 +0200
From: Krzysztof Kozlowski <k.kozlowski@...sung.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Russell King <linux@....linux.org.uk>,
Dan Williams <dan.j.williams@...el.com>,
Vinod Koul <vinod.koul@...el.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
dmaengine@...r.kernel.org, Grant Likely <grant.likely@...aro.org>,
Lars-Peter Clausen <lars@...afoo.de>,
Michal Simek <michal.simek@...inx.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Randy Dunlap <rdunlap@...radead.org>,
Alan Stern <stern@...land.harvard.edu>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
Kyungmin Park <kyungmin.park@...sung.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [PATCH v7 4/5] dma: pl330: add Power Management support
On śro, 2014-10-15 at 09:19 +0200, Ulf Hansson wrote:
> On 24 September 2014 15:50, Krzysztof Kozlowski <k.kozlowski@...sung.com> wrote:
> > This patch adds both normal PM suspend/resume support and runtime PM
> > support to pl330 DMA engine driver.
> >
> > The runtime power management for pl330 DMA driver allows gating of AMBA
> > clock (PDMA) in FSYS clock domain, when the device is not processing any
> > requests. This is necessary to enter low power modes on Exynos SoCs
> > (e.g. LPA on Exynos4x12 or W-AFTR on Exynos3250).
> >
> > Runtime PM resuming of the device may happen in atomic context (during
> > call device_issue_pending()) so pm_runtime_irq_safe() is used. This will
> > lead only to disabling/enabling of the clock but this is sufficient for
> > gating the clock and for reducing energy usage.
> >
> > During system sleep the AMBA bus clock is also unprepared.
> >
> > Suggested-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
>
> Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
Thanks for review!
You pointed one issue with patch 2/5 off-the-list. I'll wait for merge
window to end, fix it and re-send.
Best regards,
Krzysztof
>
> Kind regards
> Uffe
>
> > ---
> > drivers/dma/pl330.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++++++---
> > 1 file changed, 90 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
> > index 4839bfa74a10..b123431e62ed 100644
> > --- a/drivers/dma/pl330.c
> > +++ b/drivers/dma/pl330.c
> > @@ -27,6 +27,7 @@
> > #include <linux/of.h>
> > #include <linux/of_dma.h>
> > #include <linux/err.h>
> > +#include <linux/pm_runtime.h>
> >
> > #include "dmaengine.h"
> > #define PL330_MAX_CHAN 8
> > @@ -265,6 +266,9 @@ static unsigned cmd_line;
> >
> > #define NR_DEFAULT_DESC 16
> >
> > +/* Delay for runtime PM autosuspend, ms */
> > +#define PL330_AUTOSUSPEND_DELAY 20
> > +
> > /* Populated by the PL330 core driver for DMA API driver's info */
> > struct pl330_config {
> > u32 periph_id;
> > @@ -1958,6 +1962,7 @@ static void pl330_tasklet(unsigned long data)
> > struct dma_pl330_chan *pch = (struct dma_pl330_chan *)data;
> > struct dma_pl330_desc *desc, *_dt;
> > unsigned long flags;
> > + bool power_down = false;
> >
> > spin_lock_irqsave(&pch->lock, flags);
> >
> > @@ -1972,10 +1977,17 @@ static void pl330_tasklet(unsigned long data)
> > /* Try to submit a req imm. next to the last completed cookie */
> > fill_queue(pch);
> >
> > - /* Make sure the PL330 Channel thread is active */
> > - spin_lock(&pch->thread->dmac->lock);
> > - _start(pch->thread);
> > - spin_unlock(&pch->thread->dmac->lock);
> > + if (list_empty(&pch->work_list)) {
> > + spin_lock(&pch->thread->dmac->lock);
> > + _stop(pch->thread);
> > + spin_unlock(&pch->thread->dmac->lock);
> > + power_down = true;
> > + } else {
> > + /* Make sure the PL330 Channel thread is active */
> > + spin_lock(&pch->thread->dmac->lock);
> > + _start(pch->thread);
> > + spin_unlock(&pch->thread->dmac->lock);
> > + }
> >
> > while (!list_empty(&pch->completed_list)) {
> > dma_async_tx_callback callback;
> > @@ -1990,6 +2002,12 @@ static void pl330_tasklet(unsigned long data)
> > if (pch->cyclic) {
> > desc->status = PREP;
> > list_move_tail(&desc->node, &pch->work_list);
> > + if (power_down) {
> > + spin_lock(&pch->thread->dmac->lock);
> > + _start(pch->thread);
> > + spin_unlock(&pch->thread->dmac->lock);
> > + power_down = false;
> > + }
> > } else {
> > desc->status = FREE;
> > list_move_tail(&desc->node, &pch->dmac->desc_pool);
> > @@ -2004,6 +2022,12 @@ static void pl330_tasklet(unsigned long data)
> > }
> > }
> > spin_unlock_irqrestore(&pch->lock, flags);
> > +
> > + /* If work list empty, power down */
> > + if (power_down) {
> > + pm_runtime_mark_last_busy(pch->dmac->ddma.dev);
> > + pm_runtime_put_autosuspend(pch->dmac->ddma.dev);
> > + }
> > }
> >
> > bool pl330_filter(struct dma_chan *chan, void *param)
> > @@ -2073,6 +2097,7 @@ static int pl330_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd, unsigned
> >
> > switch (cmd) {
> > case DMA_TERMINATE_ALL:
> > + pm_runtime_get_sync(pl330->ddma.dev);
> > spin_lock_irqsave(&pch->lock, flags);
> >
> > spin_lock(&pl330->lock);
> > @@ -2099,10 +2124,15 @@ static int pl330_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd, unsigned
> > dma_cookie_complete(&desc->txd);
> > }
> >
> > + if (!list_empty(&pch->work_list))
> > + pm_runtime_put(pl330->ddma.dev);
> > +
> > list_splice_tail_init(&pch->submitted_list, &pl330->desc_pool);
> > list_splice_tail_init(&pch->work_list, &pl330->desc_pool);
> > list_splice_tail_init(&pch->completed_list, &pl330->desc_pool);
> > spin_unlock_irqrestore(&pch->lock, flags);
> > + pm_runtime_mark_last_busy(pl330->ddma.dev);
> > + pm_runtime_put_autosuspend(pl330->ddma.dev);
> > break;
> > case DMA_SLAVE_CONFIG:
> > slave_config = (struct dma_slave_config *)arg;
> > @@ -2138,6 +2168,7 @@ static void pl330_free_chan_resources(struct dma_chan *chan)
> >
> > tasklet_kill(&pch->task);
> >
> > + pm_runtime_get_sync(pch->dmac->ddma.dev);
> > spin_lock_irqsave(&pch->lock, flags);
> >
> > pl330_release_channel(pch->thread);
> > @@ -2147,6 +2178,8 @@ static void pl330_free_chan_resources(struct dma_chan *chan)
> > list_splice_tail_init(&pch->work_list, &pch->dmac->desc_pool);
> >
> > spin_unlock_irqrestore(&pch->lock, flags);
> > + pm_runtime_mark_last_busy(pch->dmac->ddma.dev);
> > + pm_runtime_put_autosuspend(pch->dmac->ddma.dev);
> > }
> >
> > static enum dma_status
> > @@ -2162,6 +2195,15 @@ static void pl330_issue_pending(struct dma_chan *chan)
> > unsigned long flags;
> >
> > spin_lock_irqsave(&pch->lock, flags);
> > + if (list_empty(&pch->work_list)) {
> > + /*
> > + * Warn on nothing pending. Empty submitted_list may
> > + * break our pm_runtime usage counter as it is
> > + * updated on work_list emptiness status.
> > + */
> > + WARN_ON(list_empty(&pch->submitted_list));
> > + pm_runtime_get_sync(pch->dmac->ddma.dev);
> > + }
> > list_splice_tail_init(&pch->submitted_list, &pch->work_list);
> > spin_unlock_irqrestore(&pch->lock, flags);
> >
> > @@ -2585,6 +2627,41 @@ static int pl330_dma_device_slave_caps(struct dma_chan *dchan,
> > return 0;
> > }
> >
> > +/*
> > + * Assume that IRQ safe runtime PM is chosen in probe and amba bus driver
> > + * will only disable/enable the clock in runtime PM suspend/resume.
> > + */
> > +static int __maybe_unused pl330_suspend(struct device *dev)
> > +{
> > + struct amba_device *pcdev = to_amba_device(dev);
> > + int ret;
> > +
> > + ret = pm_runtime_force_suspend(dev);
> > + if (ret)
> > + return ret;
> > +
> > + amba_pclk_unprepare(pcdev);
> > +
> > + return 0;
> > +}
> > +
> > +static int __maybe_unused pl330_resume(struct device *dev)
> > +{
> > + struct amba_device *pcdev = to_amba_device(dev);
> > +
> > + amba_pclk_prepare(pcdev);
> > +
> > + /*
> > + * TODO: Idea for future. The device should not be woken up after
> > + * system resume if it is not needed. It could stay runtime suspended
> > + * waiting for DMA requests. However for safe suspend and resume we
> > + * forcibly resume the device here.
> > + */
> > + return pm_runtime_force_resume(dev);
> > +}
> > +
> > +static SIMPLE_DEV_PM_OPS(pl330_pm, pl330_suspend, pl330_resume);
> > +
> > static int
> > pl330_probe(struct amba_device *adev, const struct amba_id *id)
> > {
> > @@ -2738,6 +2815,12 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id)
> > pcfg->data_buf_dep, pcfg->data_bus_width / 8, pcfg->num_chan,
> > pcfg->num_peri, pcfg->num_events);
> >
> > + pm_runtime_irq_safe(&adev->dev);
> > + pm_runtime_use_autosuspend(&adev->dev);
> > + pm_runtime_set_autosuspend_delay(&adev->dev, PL330_AUTOSUSPEND_DELAY);
> > + pm_runtime_mark_last_busy(&adev->dev);
> > + pm_runtime_put_autosuspend(&adev->dev);
> > +
> > return 0;
> > probe_err3:
> > /* Idle the DMAC */
> > @@ -2764,6 +2847,8 @@ static int pl330_remove(struct amba_device *adev)
> > struct pl330_dmac *pl330 = amba_get_drvdata(adev);
> > struct dma_pl330_chan *pch, *_p;
> >
> > + pm_runtime_get_noresume(pl330->ddma.dev);
> > +
> > if (adev->dev.of_node)
> > of_dma_controller_free(adev->dev.of_node);
> >
> > @@ -2802,6 +2887,7 @@ static struct amba_driver pl330_driver = {
> > .drv = {
> > .owner = THIS_MODULE,
> > .name = "dma-pl330",
> > + .pm = &pl330_pm,
> > },
> > .id_table = pl330_ids,
> > .probe = pl330_probe,
> > --
> > 1.9.1
> >
--
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