Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757584Ab3DAGK3 (ORCPT ); Mon, 1 Apr 2013 02:10:29 -0400 Received: from mail-wi0-f181.google.com ([209.85.212.181]:64488 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757063Ab3DAGK1 (ORCPT ); Mon, 1 Apr 2013 02:10:27 -0400 MIME-Version: 1.0 In-Reply-To: <5159234E.8080105@ti.com> References: <1364460632-21697-1-git-send-email-prabhakar.csengg@gmail.com> <1650338.UonQ4LqB70@avalon> <3365178.uRYh2rr3nD@avalon> <5159234E.8080105@ti.com> From: Prabhakar Lad Date: Mon, 1 Apr 2013 11:40:06 +0530 Message-ID: Subject: Re: [PATCH] davinci: vpif: add pm_runtime support To: Sekhar Nori Cc: Laurent Pinchart , DLOS , LMML , LKML , Mauro Carvalho Chehab , Hans Verkuil , Sakari Ailus 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: 3337 Lines: 91 Hi Sekhar, On Mon, Apr 1, 2013 at 11:33 AM, Sekhar Nori wrote: > On 3/28/2013 3:50 PM, Prabhakar Lad wrote: >> 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 ? > > Unless you need the clk handle to get the clock rate or something, you > should simply rely on runtime PM calls to enable clocks for you and not > have any clk API call at all in your driver. > Thanks this helps!, I'll post a v2 fixing it. Regards, --Prabhakar > Thanks, > Sekhar -- 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/