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Date: Tue, 17 Mar 2015 10:35:03 +0000
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Paul Walmsley <paul@pwsan.com>
Cc: linux-tegra@vger.kernel.org, linux-arm-kernel@vger.kernel.org,
        Alexandre Courbot <gnurou@gmail.com>,
        Stephen Warren <swarren@wwwdotorg.org>, linux-kernel@vger.kernel.org,
        Thierry Reding <thierry.reding@gmail.com>,
        Hiroshi DOYU <hdoyu@nvidia.com>
Subject: Re: [PATCH 2/3] amba: tegra-ahb: use correct base address for future
 chip support
Message-ID: <20150317103503.GT8656@n2100.arm.linux.org.uk>
References: <20150317083221.32662.14647.stgit@baseline>
 <20150317083221.32662.7448.stgit@baseline>
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On Tue, Mar 17, 2015 at 01:32:21AM -0700, Paul Walmsley wrote:
>  static inline u32 gizmo_readl(struct tegra_ahb *ahb, u32 offset)
>  {
> -	return readl(ahb->regs - 4 + offset);
> +	return readl(ahb->regs + ahb->offset + offset);
>  }
>  
>  static inline void gizmo_writel(struct tegra_ahb *ahb, u32 value, u32 offset)
>  {
> -	writel(value, ahb->regs - 4 + offset);
> +	writel(value, ahb->regs + ahb->offset + offset);

Rather than storing the offset...

> @@ -262,18 +283,15 @@ static int tegra_ahb_probe(struct platform_device *pdev)
>  	if (IS_ERR(ahb->regs))
>  		return PTR_ERR(ahb->regs);
>  
> +	ad = of_id->data;
>  	ahb->dev = &pdev->dev;
> +	ahb->offset = ad->offset;

What about 

	ahb->regs += ad->offset;

here and avoid the addition and extra loads on every access.

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