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 v4 10/14] dmaengine: tegra-apb: Keep clock enabled only during of DMA transfer
Date: Wed, 15 Jan 2020 10:08:25 +0000 [thread overview]
Message-ID: <5ae55a09-a1be-d93b-80f5-6ad3d712cb93@nvidia.com> (raw)
In-Reply-To: <20200112173006.29863-11-digetx@gmail.com>
On 12/01/2020 17:30, 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 | 43 ++++++++++++++++++++++-------------
> 1 file changed, 27 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> index cc4a9ca20780..b9d8e57eaf54 100644
> --- a/drivers/dma/tegra20-apb-dma.c
> +++ b/drivers/dma/tegra20-apb-dma.c
> @@ -436,6 +436,8 @@ static void tegra_dma_stop(struct tegra_dma_channel *tdc)
> tdc_write(tdc, TEGRA_APBDMA_CHAN_STATUS, status);
> }
> tdc->busy = false;
> +
> + pm_runtime_put(tdc->tdma->dev);
Is this the right place to call put? Seems that in terminate_all resume
is called after stop which will access the registers.
> }
>
> static void tegra_dma_start(struct tegra_dma_channel *tdc,
> @@ -500,18 +502,25 @@ static void tegra_dma_configure_for_next(struct tegra_dma_channel *tdc,
> tegra_dma_resume(tdc);
> }
>
> -static void tdc_start_head_req(struct tegra_dma_channel *tdc)
> +static bool tdc_start_head_req(struct tegra_dma_channel *tdc)
> {
> struct tegra_dma_sg_req *sg_req;
> + int err;
>
> if (list_empty(&tdc->pending_sg_req))
> - return;
> + return false;
> +
> + err = pm_runtime_get_sync(tdc->tdma->dev);
> + if (WARN_ON_ONCE(err < 0))
> + return false;
>
> sg_req = list_first_entry(&tdc->pending_sg_req, typeof(*sg_req), node);
> tegra_dma_start(tdc, sg_req);
> sg_req->configured = true;
> sg_req->words_xferred = 0;
> tdc->busy = true;
> +
> + return true;
> }
>
> static void tdc_configure_next_head_desc(struct tegra_dma_channel *tdc)
> @@ -615,6 +624,8 @@ static void handle_once_dma_done(struct tegra_dma_channel *tdc,
> }
> list_add_tail(&sgreq->node, &tdc->free_sg_req);
>
> + pm_runtime_put(tdc->tdma->dev);
> +
> /* Do not start DMA if it is going to be terminate */
> if (to_terminate || list_empty(&tdc->pending_sg_req))
> return;
> @@ -730,9 +741,7 @@ static void tegra_dma_issue_pending(struct dma_chan *dc)
> dev_err(tdc2dev(tdc), "No DMA request\n");
> goto end;
> }
> - if (!tdc->busy) {
> - tdc_start_head_req(tdc);
> -
> + if (!tdc->busy && tdc_start_head_req(tdc)) {
> /* Continuous single mode: Configure next req */
> if (tdc->cyclic) {
> /*
> @@ -1280,22 +1289,15 @@ 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 +1330,6 @@ 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;
> }
> @@ -1428,11 +1429,16 @@ static int tegra_dma_probe(struct platform_device *pdev)
>
> spin_lock_init(&tdma->global_lock);
>
> + ret = clk_prepare(tdma->dma_clk);
> + if (ret)
> + return ret;
> +
> + pm_runtime_irq_safe(&pdev->dev);
> pm_runtime_enable(&pdev->dev);
> if (!pm_runtime_enabled(&pdev->dev)) {
> ret = tegra_dma_runtime_resume(&pdev->dev);
> if (ret)
> - return ret;
> + goto err_clk_unprepare;
> } else {
> ret = pm_runtime_get_sync(&pdev->dev);
There is a get here but I don't see a put in probe.
Jon
--
nvpublic
next prev parent reply other threads:[~2020-01-15 10:08 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-12 17:29 [PATCH v4 00/14] NVIDIA Tegra APB DMA driver fixes and improvements Dmitry Osipenko
2020-01-12 17:29 ` [PATCH v4 01/14] dmaengine: tegra-apb: Fix use-after-free Dmitry Osipenko
2020-01-14 15:09 ` Jon Hunter
2020-01-14 20:33 ` Dmitry Osipenko
2020-01-15 9:00 ` Jon Hunter
2020-01-16 20:10 ` Dmitry Osipenko
2020-01-28 14:02 ` Jon Hunter
2020-01-28 14:51 ` Dmitry Osipenko
2020-01-29 0:12 ` Dmitry Osipenko
2020-01-29 10:42 ` Jon Hunter
2020-01-12 17:29 ` [PATCH v4 02/14] dmaengine: tegra-apb: Implement synchronization callback Dmitry Osipenko
2020-01-14 15:15 ` Jon Hunter
2020-01-14 21:02 ` Dmitry Osipenko
2020-01-15 9:18 ` Jon Hunter
2020-01-15 10:25 ` Jon Hunter
2020-01-12 17:29 ` [PATCH v4 03/14] dmaengine: tegra-apb: Prevent race conditions on channel's freeing Dmitry Osipenko
2020-01-14 15:16 ` Jon Hunter
2020-01-12 17:29 ` [PATCH v4 04/14] dmaengine: tegra-apb: Clean up tasklet releasing Dmitry Osipenko
2020-01-14 15:36 ` Jon Hunter
2020-01-12 17:29 ` [PATCH v4 05/14] dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list Dmitry Osipenko
2020-01-14 15:43 ` Jon Hunter
2020-01-12 17:29 ` [PATCH v4 06/14] dmaengine: tegra-apb: Use devm_platform_ioremap_resource Dmitry Osipenko
2020-01-14 15:44 ` Jon Hunter
2020-01-12 17:29 ` [PATCH v4 07/14] dmaengine: tegra-apb: Use devm_request_irq Dmitry Osipenko
2020-01-14 15:44 ` Jon Hunter
2020-01-12 17:30 ` [PATCH v4 08/14] dmaengine: tegra-apb: Fix coding style problems Dmitry Osipenko
2020-01-15 9:49 ` Jon Hunter
2020-01-16 17:37 ` Dmitry Osipenko
2020-01-28 14:05 ` Jon Hunter
2020-01-28 15:01 ` Dmitry Osipenko
2020-01-12 17:30 ` [PATCH v4 09/14] dmaengine: tegra-apb: Clean up runtime PM teardown Dmitry Osipenko
2020-01-15 9:57 ` Jon Hunter
2020-01-16 17:18 ` Dmitry Osipenko
2020-01-12 17:30 ` [PATCH v4 10/14] dmaengine: tegra-apb: Keep clock enabled only during of DMA transfer Dmitry Osipenko
2020-01-15 10:08 ` Jon Hunter [this message]
2020-01-16 17:01 ` Dmitry Osipenko
2020-01-12 17:30 ` [PATCH v4 11/14] dmaengine: tegra-apb: Clean up suspend-resume Dmitry Osipenko
2020-01-21 21:23 ` Dmitry Osipenko
2020-01-28 14:10 ` Jon Hunter
2020-01-28 14:53 ` Dmitry Osipenko
2020-01-12 17:30 ` [PATCH v4 12/14] dmaengine: tegra-apb: Add missing of_dma_controller_free Dmitry Osipenko
2020-01-15 10:10 ` Jon Hunter
2020-01-12 17:30 ` [PATCH v4 13/14] dmaengine: tegra-apb: Allow to compile as a loadable kernel module Dmitry Osipenko
2020-01-15 10:10 ` Jon Hunter
2020-01-12 17:30 ` [PATCH v4 14/14] dmaengine: tegra-apb: Remove MODULE_ALIAS Dmitry Osipenko
2020-01-15 10:11 ` Jon Hunter
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