dmaengine Archive on lore.kernel.org
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From: Jon Hunter <jonathanh@nvidia.com>
To: "Dmitry Osipenko" <digetx@gmail.com>,
	"Laxman Dewangan" <ldewangan@nvidia.com>,
	"Vinod Koul" <vkoul@kernel.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Thierry Reding" <thierry.reding@gmail.com>,
	"Michał Mirosław" <mirq-linux@rere.qmqm.pl>
Cc: <dmaengine@vger.kernel.org>, <linux-tegra@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v7 14/19] dmaengine: tegra-apb: Keep clock enabled only during of DMA transfer
Date: Thu, 6 Feb 2020 13:50:35 +0000
Message-ID: <ca0f71ef-ba16-73bc-d904-1f5351c69931@nvidia.com> (raw)
In-Reply-To: <20200202222854.18409-15-digetx@gmail.com>


On 02/02/2020 22:28, Dmitry Osipenko wrote:
> It's a bit impractical to enable hardware's clock at the time of DMA
> channel's allocation because most of DMA client drivers allocate DMA
> channel at the time of the driver's probing, and thus, DMA clock is kept
> always-enabled in practice, defeating the whole purpose of runtime PM.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/dma/tegra20-apb-dma.c | 35 ++++++++++++++++++++++++-----------
>  1 file changed, 24 insertions(+), 11 deletions(-)
What about something like ...

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 22b88ccff05d..d60532f19a43 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -570,6 +570,7 @@ static bool handle_continuous_head_request(struct tegra_dma_channel *tdc,
 	if (list_empty(&tdc->pending_sg_req)) {
 		dev_err(tdc2dev(tdc), "DMA is running without req\n");
 		tegra_dma_stop(tdc);
+		pm_runtime_put(tdc->tdma->dev);
 		return false;
 	}
 
@@ -581,6 +582,7 @@ static bool handle_continuous_head_request(struct tegra_dma_channel *tdc,
 	hsgreq = list_first_entry(&tdc->pending_sg_req, typeof(*hsgreq), node);
 	if (!hsgreq->configured) {
 		tegra_dma_stop(tdc);
+		pm_runtime_put(tdc->tdma->dev);
 		dev_err(tdc2dev(tdc), "Error in DMA transfer, aborting DMA\n");
 		tegra_dma_abort_all(tdc);
 		return false;
@@ -616,9 +618,14 @@ static void handle_once_dma_done(struct tegra_dma_channel *tdc,
 	list_add_tail(&sgreq->node, &tdc->free_sg_req);
 
 	/* Do not start DMA if it is going to be terminate */
-	if (to_terminate || list_empty(&tdc->pending_sg_req))
+	if (to_terminate)
 		return;
 
+	if (list_empty(&tdc->pending_sg_req)) {
+		pm_runtime_put(tdc->tdma->dev);
+		return;
+	}
+
 	tdc_start_head_req(tdc);
 }
 
@@ -731,6 +738,10 @@ static void tegra_dma_issue_pending(struct dma_chan *dc)
 		goto end;
 	}
 	if (!tdc->busy) {
+		err = pm_runtime_get_sync(tdc->tdma->dev);
+		if (err < 0)
+			return err;
+
 		tdc_start_head_req(tdc);
 
 		/* Continuous single mode: Configure next req */
@@ -786,6 +797,8 @@ static int tegra_dma_terminate_all(struct dma_chan *dc)
 	}
 	tegra_dma_resume(tdc);
 
+	pm_runtime_put(tdc->tdma->dev);
+
 skip_dma_stop:
 	tegra_dma_abort_all(tdc);
 
@@ -1280,22 +1293,15 @@ tegra_dma_prep_dma_cyclic(struct dma_chan *dc, dma_addr_t buf_addr,
 static int tegra_dma_alloc_chan_resources(struct dma_chan *dc)
 {
 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
-	struct tegra_dma *tdma = tdc->tdma;
-	int ret;
 
 	dma_cookie_init(&tdc->dma_chan);
 
-	ret = pm_runtime_get_sync(tdma->dev);
-	if (ret < 0)
-		return ret;
-
 	return 0;
 }
 
 static void tegra_dma_free_chan_resources(struct dma_chan *dc)
 {
 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
-	struct tegra_dma *tdma = tdc->tdma;
 	struct tegra_dma_desc *dma_desc;
 	struct tegra_dma_sg_req *sg_req;
 	struct list_head dma_desc_list;
@@ -1328,7 +1334,6 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
 		list_del(&sg_req->node);
 		kfree(sg_req);
 	}
-	pm_runtime_put(tdma->dev);
 
 	tdc->slave_id = TEGRA_APBDMA_SLAVE_ID_INVALID;
 }

-- 
nvpublic

  reply index

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-02 22:28 [PATCH v7 00/19] NVIDIA Tegra APB DMA driver fixes and improvements Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 01/19] dmaengine: tegra-apb: Fix use-after-free Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 02/19] dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 03/19] dmaengine: tegra-apb: Implement synchronization hook Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 04/19] dmaengine: tegra-apb: Prevent race conditions on channel's freeing Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 05/19] dmaengine: tegra-apb: Clean up tasklet releasing Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 06/19] dmaengine: tegra-apb: Use devm_platform_ioremap_resource Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 07/19] dmaengine: tegra-apb: Use devm_request_irq Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 08/19] dmaengine: tegra-apb: Fix coding style problems Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 09/19] dmaengine: tegra-apb: Remove unneeded initialization of tdc->config_init Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 10/19] dmaengine: tegra-apb: Remove assumptions about unavailable runtime PM Dmitry Osipenko
2020-02-04 14:51   ` Jon Hunter
2020-02-02 22:28 ` [PATCH v7 11/19] dmaengine: tegra-apb: Remove pending_sg_req checking from tdc_start_head_req Dmitry Osipenko
2020-02-04 14:53   ` Jon Hunter
2020-02-02 22:28 ` [PATCH v7 12/19] dmaengine: tegra-apb: Remove handling of unrealistic error condition Dmitry Osipenko
2020-02-04 11:52   ` Jon Hunter
2020-02-04 22:17     ` Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 13/19] dmaengine: tegra-apb: Don't stop cyclic DMA in a case of " Dmitry Osipenko
2020-02-04 12:02   ` Jon Hunter
2020-02-04 15:55     ` Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 14/19] dmaengine: tegra-apb: Keep clock enabled only during of DMA transfer Dmitry Osipenko
2020-02-06 13:50   ` Jon Hunter [this message]
2020-02-06 14:31     ` Dmitry Osipenko
2020-02-06 14:33       ` Jon Hunter
2020-02-02 22:28 ` [PATCH v7 15/19] dmaengine: tegra-apb: Clean up suspend-resume Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 16/19] dmaengine: tegra-apb: Add missing of_dma_controller_free Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 17/19] dmaengine: tegra-apb: Allow to compile as a loadable kernel module Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 18/19] dmaengine: tegra-apb: Remove MODULE_ALIAS Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 19/19] dmaengine: tegra-apb: Support COMPILE_TEST Dmitry Osipenko

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