Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755676Ab3C1KVR (ORCPT ); Thu, 28 Mar 2013 06:21:17 -0400 Received: from mail-qe0-f49.google.com ([209.85.128.49]:40519 "EHLO mail-qe0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755492Ab3C1KVP (ORCPT ); Thu, 28 Mar 2013 06:21:15 -0400 MIME-Version: 1.0 In-Reply-To: <3365178.uRYh2rr3nD@avalon> References: <1364460632-21697-1-git-send-email-prabhakar.csengg@gmail.com> <1650338.UonQ4LqB70@avalon> <3365178.uRYh2rr3nD@avalon> From: Prabhakar Lad Date: Thu, 28 Mar 2013 15:50:55 +0530 Message-ID: Subject: Re: [PATCH] davinci: vpif: add pm_runtime support To: Laurent Pinchart Cc: DLOS , LMML , LKML , Mauro Carvalho Chehab , Hans Verkuil , Sakari Ailus , Sekhar Nori Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2879 Lines: 84 Hi Laurent, On Thu, Mar 28, 2013 at 3:40 PM, Laurent Pinchart wrote: > Hi Prabhakar, > > On Thursday 28 March 2013 15:36:11 Prabhakar Lad wrote: >> On Thu, Mar 28, 2013 at 2:39 PM, Laurent Pinchart wrote: >> > On Thursday 28 March 2013 14:20:32 Prabhakar lad wrote: >> >> From: Lad, Prabhakar >> >> >> >> Add pm_runtime support to the TI Davinci VPIF driver. >> >> Along side this patch replaces clk_get() with devm_clk_get() >> >> to simplify the error handling. >> >> >> >> Signed-off-by: Lad, Prabhakar >> >> --- >> >> >> >> drivers/media/platform/davinci/vpif.c | 21 +++++++++++---------- >> >> 1 files changed, 11 insertions(+), 10 deletions(-) >> >> >> >> diff --git a/drivers/media/platform/davinci/vpif.c >> >> b/drivers/media/platform/davinci/vpif.c index 28638a8..7d14625 100644 >> >> --- a/drivers/media/platform/davinci/vpif.c >> >> +++ b/drivers/media/platform/davinci/vpif.c > > [snip] > >> >> @@ -439,12 +440,17 @@ static int vpif_probe(struct platform_device *pdev) >> >> goto fail; >> >> } >> >> >> >> - vpif_clk = clk_get(&pdev->dev, "vpif"); >> >> + vpif_clk = devm_clk_get(&pdev->dev, "vpif"); >> >> if (IS_ERR(vpif_clk)) { >> >> status = PTR_ERR(vpif_clk); >> >> goto clk_fail; >> >> } >> >> >> >> - clk_prepare_enable(vpif_clk); >> >> + clk_put(vpif_clk); >> > >> > Why do you need to call clk_put() here ? >> >> The above check is to see if the clock is provided, once done >> we free it using clk_put(). > > In that case you shouldn't use devm_clk_get(), otherwise clk_put() will be > called again automatically at remove() time. > Yes agreed it should be clk_get() only. >> >> + pm_runtime_enable(&pdev->dev); >> >> + pm_runtime_resume(&pdev->dev); >> >> + >> >> + pm_runtime_get(&pdev->dev); >> > >> > Does runtime PM automatically handle your clock ? If so can't you remove >> > clock handling from the driver completely ? >> >> Yes pm runtime take care of enabling/disabling the clocks >> so that we don't have to do it in drivers. I believe clock >> handling is removed with this patch, with just devm_clk_get() remaining ;) > > When is the clk_get() call expected to fail ? If the clock is provided by the > SoC and always available, can't the check be removed completely ? > Yes I agree with you it can be removed completely assuming the clock is always available from the Soc. But may be I need feedback from others Hans/Sekhar what do you suggest ? Regards, --Prabhakar > -- > Regards, > > Laurent Pinchart > -- 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/