Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752450AbdIUAgn (ORCPT ); Wed, 20 Sep 2017 20:36:43 -0400 Received: from lelnx194.ext.ti.com ([198.47.27.80]:55639 "EHLO lelnx194.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751652AbdIUAgl (ORCPT ); Wed, 20 Sep 2017 20:36:41 -0400 Subject: Re: [v2,3/3] can: m_can: Add PM Runtime To: Sekhar Nori , , , , , , , , References: <20170724225142.19975-4-fcooper@ti.com> <8037f5f9-d51f-99c3-f2e8-62c90e56a6fa@ti.com> CC: Linux OMAP List , Alexandre Belloni , Wenyou Yang , =?UTF-8?Q?Mario_H=c3=bcttel?= From: Franklin S Cooper Jr Message-ID: Date: Wed, 20 Sep 2017 19:36:15 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <8037f5f9-d51f-99c3-f2e8-62c90e56a6fa@ti.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [172.22.140.142] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3385 Lines: 108 On 08/24/2017 03:30 AM, Sekhar Nori wrote: > + OMAP mailing list > > On Tuesday 25 July 2017 04:21 AM, Franklin Cooper wrote: >> Add support for PM Runtime which is the new way to handle managing clocks. >> However, to avoid breaking SoCs not using PM_RUNTIME leave the old clk >> management approach in place. > > Since hclk is the interface clock, I think at a minimum there needs to > be an assumption that pm_runtime_get_sync() will enable that clock and > make the module ready for access. > > The only in-kernel user of this driver seems to be an atmel SoC. I am > ccing folks who added support for M_CAN on that SoC to see if hclk > management can be left to pm_runtime*() on their SoC. > > If they are okay, I think its a good to atleast drop explicit hclk > enable disable in the driver. That way, we avoid double enable/disable > of interface clock (hclk). Wenyou, Do you foresee this being a problem on your board? If not I can send a v3 removing these clk_enable and clk_disable calls and it would be great if you can test it out and provide your tested by. > >> >> PM_RUNTIME is required by OMAP based devices to handle clock management. >> Therefore, this allows future Texas Instruments SoCs that have the MCAN IP >> to work with this driver. >> >> Signed-off-by: Franklin S Cooper Jr > > Thanks, > Sekhar > >> --- >> drivers/net/can/m_can/m_can.c | 13 +++++++++++++ >> 1 file changed, 13 insertions(+) >> >> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c >> index ea48e59..93e23f5 100644 >> --- a/drivers/net/can/m_can/m_can.c >> +++ b/drivers/net/can/m_can/m_can.c >> @@ -23,6 +23,7 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> >> @@ -633,11 +634,15 @@ static int m_can_clk_start(struct m_can_priv *priv) >> if (err) >> clk_disable_unprepare(priv->hclk); >> >> + pm_runtime_get_sync(priv->device); >> + >> return err; >> } >> >> static void m_can_clk_stop(struct m_can_priv *priv) >> { >> + pm_runtime_put_sync(priv->device); >> + >> clk_disable_unprepare(priv->cclk); >> clk_disable_unprepare(priv->hclk); >> } >> @@ -1582,6 +1587,8 @@ static int m_can_plat_probe(struct platform_device *pdev) >> /* Enable clocks. Necessary to read Core Release in order to determine >> * M_CAN version >> */ >> + pm_runtime_enable(&pdev->dev); >> + >> ret = clk_prepare_enable(hclk); >> if (ret) >> goto disable_hclk_ret; >> @@ -1626,6 +1633,8 @@ static int m_can_plat_probe(struct platform_device *pdev) >> */ >> tx_fifo_size = mram_config_vals[7]; >> >> + pm_runtime_get_sync(&pdev->dev); >> + >> /* allocate the m_can device */ >> dev = alloc_m_can_dev(pdev, addr, tx_fifo_size); >> if (!dev) { >> @@ -1670,6 +1679,7 @@ static int m_can_plat_probe(struct platform_device *pdev) >> disable_hclk_ret: >> clk_disable_unprepare(hclk); >> failed_ret: >> + pm_runtime_put_sync(&pdev->dev); >> return ret; >> } >> >> @@ -1726,6 +1736,9 @@ static int m_can_plat_remove(struct platform_device *pdev) >> struct net_device *dev = platform_get_drvdata(pdev); >> >> unregister_m_can_dev(dev); >> + >> + pm_runtime_disable(&pdev->dev); >> + >> platform_set_drvdata(pdev, NULL); >> >> free_m_can_dev(dev); >> >