From mboxrd@z Thu Jan 1 00:00:00 1970 From: Krzysztof Kozlowski Subject: Re: [PATCH v9 3/4] dma: pl330: add Power Management support Date: Wed, 05 Nov 2014 15:21:39 +0100 Message-ID: <1415197299.30831.10.camel@AMDC1943> References: <1415105570-7871-1-git-send-email-k.kozlowski@samsung.com> <1415105570-7871-4-git-send-email-k.kozlowski@samsung.com> <20141105140116.GN1870@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mailout3.w1.samsung.com ([210.118.77.13]:40447 "EHLO mailout3.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754715AbaKEOVo (ORCPT ); Wed, 5 Nov 2014 09:21:44 -0500 In-reply-to: <20141105140116.GN1870@intel.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Vinod Koul Cc: "Rafael J. Wysocki" , Len Brown , Pavel Machek , Jonathan Corbet , Russell King , Dan Williams , Ulf Hansson , Alan Stern , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, Lars-Peter Clausen , Michal Simek , Kevin Hilman , Laurent Pinchart , Kyungmin Park , Marek Szyprowski , Bartlomiej Zolnierkiewicz On =C5=9Bro, 2014-11-05 at 19:31 +0530, Vinod Koul wrote: > On Tue, Nov 04, 2014 at 01:52:49PM +0100, Krzysztof Kozlowski wrote: > > bool pl330_filter(struct dma_chan *chan, void *param) > > @@ -2073,6 +2097,7 @@ static int pl330_control(struct dma_chan *cha= n, enum dma_ctrl_cmd cmd, unsigned > > =20 > > switch (cmd) { > > case DMA_TERMINATE_ALL: > > + pm_runtime_get_sync(pl330->ddma.dev); > Why do we need _get() here? If we are terminating then channel is alr= eady in > use so should be active? The runtime PM is kind a aggressive here so I think the device could be suspended in that moment. The terminate may happen some time after channel was used. >=20 > > spin_lock_irqsave(&pch->lock, flags); > > =20 > > spin_lock(&pl330->lock); > > @@ -2099,10 +2124,15 @@ static int pl330_control(struct dma_chan *c= han, enum dma_ctrl_cmd cmd, unsigned > > dma_cookie_complete(&desc->txd); > > } > > =20 > > + if (!list_empty(&pch->work_list)) > > + pm_runtime_put(pl330->ddma.dev); > Well else should be error here, so I would expect loud complains in t= hat > case here The 'else' path is fine. Just the terminate command was triggered when work_list was empty.=20 The 'else' here could be triggered easily with: echo dma0chan0 > /sys/module/dmatest/parameters/channel echo 1 > /sys/module/dmatest/parameters/run sleep 3 cat /sys/module/dmatest/parameters/run > > + > > 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 =3D (struct dma_slave_config *)arg; > > @@ -2138,6 +2168,7 @@ static void pl330_free_chan_resources(struct = dma_chan *chan) > > =20 > > tasklet_kill(&pch->task); > > =20 > > + pm_runtime_get_sync(pch->dmac->ddma.dev); > Again why do we need _get() in free callback. Hmmm... I think because of the same reason as terminate_all. It may happen after some time since last usage. The driver here stops thread which requires device resumed. >=20 > > spin_lock_irqsave(&pch->lock, flags); > > =20 > > 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); > > =20 > > spin_unlock_irqrestore(&pch->lock, flags); > > + pm_runtime_mark_last_busy(pch->dmac->ddma.dev); > > + pm_runtime_put_autosuspend(pch->dmac->ddma.dev); > > } >=20 > > + > > +static int __maybe_unused pl330_resume(struct device *dev) > > +{ > > + struct amba_device *pcdev =3D 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 suspe= nded > > + * 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); > IIUC this sets .suspend and .resume, aren't you trying to add runtime > support as well? > Did you want UNIVERSAL_DEV_PM_OPS() ? The runtime suspend and resume callbacks are provided by amba/bus.c. >=20 > > + > > 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); > > =20 > > + pm_runtime_irq_safe(&adev->dev); > > + pm_runtime_use_autosuspend(&adev->dev); > > + pm_runtime_set_autosuspend_delay(&adev->dev, PL330_AUTOSUSPEND_DE= LAY); > > + 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 *a= dev) > > struct pl330_dmac *pl330 =3D amba_get_drvdata(adev); > > struct dma_pl330_chan *pch, *_p; > > =20 > > + pm_runtime_get_noresume(pl330->ddma.dev); > > + > > if (adev->dev.of_node) > > of_dma_controller_free(adev->dev.of_node); > > =20 > > @@ -2802,6 +2887,7 @@ static struct amba_driver pl330_driver =3D { > > .drv =3D { > > .owner =3D THIS_MODULE, > > .name =3D "dma-pl330", > > + .pm =3D &pl330_pm, > > }, > > .id_table =3D pl330_ids, > > .probe =3D pl330_probe, > > --=20 > > 1.9.1 > >=20 >=20 > Last please use the right subsystem name, dmaengine is patches. Sure, I just got confused by name of directory. Thanks for looking at code, Krzysztof