linux-kernel - Re: [RFC 04/42] drivers/dma: don't check resource with devm_ioremap

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Date:	Sun, 12 May 2013 21:34:40 +0530
From:	Vinod Koul <vinod.koul@...el.com>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Wolfram Sang <wsa@...-dreams.de>, linux-kernel@...r.kernel.org,
	Dan Williams <djbw@...com>, linux-tegra@...r.kernel.org
Subject: Re: [RFC 04/42] drivers/dma: don't check resource with
 devm_ioremap_resource

On Fri, May 10, 2013 at 01:25:36PM -0600, Stephen Warren wrote:
> On 05/10/2013 11:57 AM, Wolfram Sang wrote:
> > On Fri, May 10, 2013 at 10:35:32AM -0600, Stephen Warren wrote:
> >> On 05/10/2013 02:16 AM, Wolfram Sang wrote:
> >>> devm_ioremap_resource does sanity checks on the given resource. No need to
> >>> duplicate this in the driver.
> >>
> >>> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> >>
> >>>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >>> -	if (!res) {
> >>> -		dev_err(&pdev->dev, "No mem resource for DMA\n");
> >>> -		return -EINVAL;
> >>> -	}
> >>> -
> >>>  	tdma->base_addr = devm_ioremap_resource(&pdev->dev, res);
> >>
> >> One issue here is that it's not obvious just from reading the code
> >> that's left behind that the "missing" error-checking of the
> >> platform_get_resource() return value is OK because
> >> devm_ioremap_resource() will check it "for us". Everyone now has to
> >> mentally maintain a list of exceptions where it's OK not to error-check.
> > 
> > My goal is to make not-checking the standard case with devm.
> 
> OK, if no parameters passed to any devm function every need to be
> error-checked, that'll certainly be a bit easier to remember.
Okay to remove the log message and move to devm_ but I dont agree with this
patch not returning error above. We shouldnt supress the error..

--
~Vinod
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