Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752476AbbKPJe6 (ORCPT ); Mon, 16 Nov 2015 04:34:58 -0500 Received: from hqemgate16.nvidia.com ([216.228.121.65]:2223 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751469AbbKPJe4 (ORCPT ); Mon, 16 Nov 2015 04:34:56 -0500 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Mon, 16 Nov 2015 01:23:23 -0800 Subject: Re: [PATCH V3 1/6] dmaengine: tegra-apb: Correct runtime-pm usage To: Andy Shevchenko References: <1447432783-7466-1-git-send-email-jonathanh@nvidia.com> <1447432783-7466-2-git-send-email-jonathanh@nvidia.com> CC: Laxman Dewangan , Vinod Koul , Stephen Warren , Thierry Reding , Alexandre Courbot , dmaengine , "linux-tegra@vger.kernel.org" , "linux-kernel@vger.kernel.org" From: Jon Hunter Message-ID: <5649A339.20208@nvidia.com> Date: Mon, 16 Nov 2015 09:34:49 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [10.21.132.159] X-ClientProxiedBy: UKMAIL101.nvidia.com (10.26.138.13) To UKMAIL101.nvidia.com (10.26.138.13) Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2990 Lines: 85 On 14/11/15 13:27, Andy Shevchenko wrote: > On Fri, Nov 13, 2015 at 6:39 PM, Jon Hunter wrote: >> The tegra-apb DMA driver enables runtime-pm but never calls >> pm_runtime_get/put and hence the runtime-pm callbacks are never invoked. >> The driver manages the clocks by directly calling clk_prepare_enable() >> and clk_unprepare_disable(). >> >> Fix this by replacing the clk_prepare_enable() and clk_disable_unprepare() >> with pm_runtime_get_sync() and pm_runtime_put(), respectively. Note that >> the consequence of this is that if runtime-pm is disabled, then the clocks >> will remain on the entire time the driver is loaded. However, if >> runtime-pm is disabled, then power is not most likely not a concern. >> > > Have you tested these changes somehow? Yes. > See my comments below. > >> Signed-off-by: Jon Hunter >> --- >> V3 changes: >> - Removed unnecessary update to local variables in suspend/resume >> V2 changes: >> - Fixed return value for allocating channel >> - Fixed test for return value from pm_runtime_get_sync() >> >> drivers/dma/tegra20-apb-dma.c | 43 ++++++++++++++++++------------------------- >> 1 file changed, 18 insertions(+), 25 deletions(-) >> >> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c >> index c8f79dcaaee8..f68bccf55a24 100644 >> --- a/drivers/dma/tegra20-apb-dma.c >> +++ b/drivers/dma/tegra20-apb-dma.c >> @@ -1186,10 +1186,12 @@ static int tegra_dma_alloc_chan_resources(struct dma_chan *dc) >> >> dma_cookie_init(&tdc->dma_chan); >> tdc->config_init = false; >> - ret = clk_prepare_enable(tdma->dma_clk); >> + >> + ret = pm_runtime_get_sync(tdma->dev); >> if (ret < 0) >> - dev_err(tdc2dev(tdc), "clk_prepare_enable failed: %d\n", ret); >> - return ret; >> + return ret; >> + > >> + return 0; > > This is a non-reachable code. No it is not. >> } >> >> static void tegra_dma_free_chan_resources(struct dma_chan *dc) >> @@ -1232,7 +1234,7 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc) >> list_del(&sg_req->node); >> kfree(sg_req); >> } >> - clk_disable_unprepare(tdma->dma_clk); >> + pm_runtime_put(tdma->dev); >> >> tdc->slave_id = 0; >> } >> @@ -1356,20 +1358,14 @@ static int tegra_dma_probe(struct platform_device *pdev) >> spin_lock_init(&tdma->global_lock); >> >> pm_runtime_enable(&pdev->dev); >> - if (!pm_runtime_enabled(&pdev->dev)) { >> + if (!pm_runtime_enabled(&pdev->dev)) >> ret = tegra_dma_runtime_resume(&pdev->dev); > > I didn't check, but does this bring device to powered on state? Yes. Jon -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/