linux-kernel - Re: [PATCH 2/4] dmaengine: qcom_bam_dma: clear BAM interrupt only if it is rised

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Message-ID: <6461444.oollnBsbrb@wuerfel>
Date:	Tue, 01 Dec 2015 11:29:41 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	Stanimir Varbanov <stanimir.varbanov@...aro.org>,
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org, dmaengine@...r.kernel.org,
	Vinod Koul <vinod.koul@...el.com>,
	Mark Rutland <mark.rutland@....com>,
	Archit Taneja <architt@...eaurora.org>,
	Pawel Moll <pawel.moll@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Rob Herring <robh+dt@...nel.org>,
	Andy Gross <agross@...eaurora.org>
Subject: Re: [PATCH 2/4] dmaengine: qcom_bam_dma: clear BAM interrupt only if it is rised

On Tuesday 01 December 2015 11:14:57 Stanimir Varbanov wrote:
> +       if (srcs & BAM_IRQ) {
>                 clr_mask = readl_relaxed(bam_addr(bdev, 0, BAM_IRQ_STTS));
>  
> -       /* don't allow reorder of the various accesses to the BAM registers */
> -       mb();
> +               /*
> +                * don't allow reorder of the various accesses to the BAM
> +                * registers
> +                */
> +               mb();
>  
> -       writel_relaxed(clr_mask, bam_addr(bdev, 0, BAM_IRQ_CLR));
> +               writel_relaxed(clr_mask, bam_addr(bdev, 0, BAM_IRQ_CLR));
> +       }
> 

I think the comment here should be moved: change the writel_relaxed()
to writel(), which already includes the appropriate barriers, and
add a comment at the readl_relaxed() to explain why it doesn't need
a barrier.

	Arnd
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