linux-kernel - Re: [RFC v2 2/8] video: tegra: Add syncpoint wait and interrupts

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Date:	Thu, 29 Nov 2012 11:41:50 -0700
From:	Stephen Warren <swarren@...dotorg.org>
To:	Thierry Reding <thierry.reding@...onic-design.de>
CC:	Terje Bergstrom <tbergstrom@...dia.com>,
	linux-tegra@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC v2 2/8] video: tegra: Add syncpoint wait and interrupts

On 11/29/2012 01:44 AM, Thierry Reding wrote:
> On Mon, Nov 26, 2012 at 03:19:08PM +0200, Terje Bergstrom wrote:

>> diff --git a/drivers/video/tegra/host/host1x/host1x_intr.c
>> b/drivers/video/tegra/host/host1x/host1x_intr.c
> [...]
>> +/* Spacing between sync registers */ +#define REGISTER_STRIDE 4
> 
> Erm... no. The usual way you should be doing this is either make
> the register definitions account for the stride or use accessors
> that apply the stride. You should be doing the latter anyway to
> make accesses. For example:
> 
> static inline void host1x_syncpt_writel(struct host1x *host1x, 
> unsigned long value, unsigned long offset) { writel(value,
> host1x->regs + SYNCPT_BASE + offset); }
> 
> static inline unsigned long host1x_syncpt_readl(struct host1x
> *host1x, unsigned long offset) { return readl(host1x->regs +
> SYNCPT_BASE + offset); }
> 
> Alternatively, if you want to pass the register index instead of
> the offset, you can use just multiply the offset in that function:
> 
> writel(value, host1x->regs + SYNCPT_BASE + (offset << 2));
> 
> The same can also be done with the non-syncpt registers.

It seems like reasonable documentation to replace "<< 2" with "*
REGISTER_STRIDE" here.
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