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SubjectRe: [PATCH 1/9] ARM i.MX51: Add ipu clock support
Date
On Thursday 09 December 2010, Sascha Hauer wrote:
> +static int clk_ipu_enable(struct clk *clk)
> +{
> + u32 reg;
> +
> + _clk_ccgr_enable(clk);
> +
> + /* Enable handshake with IPU when certain clock rates are changed */
> + reg = __raw_readl(MXC_CCM_CCDR);
> + reg &= ~MXC_CCM_CCDR_IPU_HS_MASK;
> + __raw_writel(reg, MXC_CCM_CCDR);
> +
> + /* Enable handshake with IPU when LPM is entered */
> + reg = __raw_readl(MXC_CCM_CLPCR);
> + reg &= ~MXC_CCM_CLPCR_BYPASS_IPU_LPM_HS;
> + __raw_writel(reg, MXC_CCM_CLPCR);
> +
> + return 0;
> +}

Why __raw_readl?

The regular accessor function for I/O registers is readl, which handles
the access correctly with regard to atomicity, I/O ordering and byteorder.

Arnd


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