Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751892Ab3ITO1I (ORCPT ); Fri, 20 Sep 2013 10:27:08 -0400 Received: from mga14.intel.com ([143.182.124.37]:21142 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751324Ab3ITO1G convert rfc822-to-8bit (ORCPT ); Fri, 20 Sep 2013 10:27:06 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.90,944,1371106800"; d="scan'208";a="297311415" Message-ID: <1379687206.10899.5.camel@smile> Subject: Re: [PATCH 30/51] DMA-API: dma: dw_dmac.c: convert to use dma_coerce_mask_and_coherent() From: Andy Shevchenko To: Russell King Cc: linux-kernel@vger.kernel.org, Viresh Kumar , Dan Williams , Vinod Koul Date: Fri, 20 Sep 2013 17:26:46 +0300 In-Reply-To: References: <20130919212235.GD12758@n2100.arm.linux.org.uk> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.8.5-2 Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1989 Lines: 59 On Thu, 2013-09-19 at 22:55 +0100, Russell King wrote: > This code sequence: > if (!pdev->dev.dma_mask) { > pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask; > pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32); > } > bypasses the architectures check on the DMA mask. It can be replaced > with dma_coerce_mask_and_coherent(), avoiding the direct initialization > of this mask. > > Signed-off-by: Russell King > --- > drivers/dma/dw/platform.c | 8 +++----- > 1 files changed, 3 insertions(+), 5 deletions(-) > > diff --git a/drivers/dma/dw/platform.c b/drivers/dma/dw/platform.c > index e35d975..453822c 100644 > --- a/drivers/dma/dw/platform.c > +++ b/drivers/dma/dw/platform.c > @@ -191,11 +191,9 @@ static int dw_probe(struct platform_device *pdev) > if (IS_ERR(chip->regs)) > return PTR_ERR(chip->regs); > > - /* Apply default dma_mask if needed */ > - if (!dev->dma_mask) { > - dev->dma_mask = &dev->coherent_dma_mask; > - dev->coherent_dma_mask = DMA_BIT_MASK(32); > - } > + err = dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32)); > + if (err) > + return err; I have at least one question. In case of new code you always assign dev->dma_mask. static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask) { dev->dma_mask = &dev->coherent_dma_mask; return dma_set_mask_and_coherent(dev, mask); } So, the question is how keep the initialized dma_mask (and should we do so by your opinion)? Additional question, who will free memory allocated for dma_mask in case if it was allocated, dma_mask initialized and then your code just substitute the address to some new value? -- Andy Shevchenko Intel Finland Oy -- 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/