[PATCH] ARM: mx3: Setup AIPS registers

[Dirk Behme]

On 28.02.2012 04:15, Fabio Estevam wrote:
> It was observed on a mx31pdk board that audio playback only worked when the bootloader was Redboot, and 
> did not work when U-boot was used. 
> 
> Comparing the sources of these bootloaders showed that the AIPS registers were not setup in U-boot.
> 
> Instead of relying on the bootloader to setup the AIPS registers, do it in the kernel so that audio
> playback can work independantly of the bootloader being used.
> 
> Copied the AIPS settings from Redboot to the kernel.
> 
> Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
> ---
>  arch/arm/mach-imx/cpu-imx31.c |   32 ++++++++++++++++++++++++++++++++
>  1 files changed, 32 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/mach-imx/cpu-imx31.c b/arch/arm/mach-imx/cpu-imx31.c
> index 3f2345f..c309d51 100644
> --- a/arch/arm/mach-imx/cpu-imx31.c
> +++ b/arch/arm/mach-imx/cpu-imx31.c
> @@ -60,3 +60,35 @@ int mx31_revision(void)
>  	return mx31_cpu_rev;
>  }
>  EXPORT_SYMBOL(mx31_revision);
> +
> +static void __init imx_set_aips(void __iomem *base)
> +{
> +	unsigned int reg;
> +/*
> + * Set all MPROTx to be non-bufferable, trusted for R/W,
> + * not forced to user-mode.
> + */
> +	__raw_writel(0x77777777, base + 0x0);
> +	__raw_writel(0x77777777, base + 0x4);
> +
> +/*
> + * Clear the on and off peripheral modules Supervisor Protect bit
> + * for SDMA to access them. Did not change the AIPS control registers
> + * (offset 0x20) access type
> + */
> +	__raw_writel(0x0, base + 0x40);
> +	__raw_writel(0x0, base + 0x44);
> +	__raw_writel(0x0, base + 0x48);
> +	__raw_writel(0x0, base + 0x4C);
> +	reg = __raw_readl(base + 0x50) & 0x00FFFFFF;
> +	__raw_writel(reg, base + 0x50);
> +}
> +
> +static int __init post_cpu_init(void)
> +{
> +	imx_set_aips(MX31_IO_ADDRESS(MX31_AIPS1_BASE_ADDR));
> +	imx_set_aips(MX31_IO_ADDRESS(MX31_AIPS2_BASE_ADDR));
> +
> +	return 0;
> +}
> +postcore_initcall(post_cpu_init);

Hmm, I'm not totally sure if we talk about the same thing, but at least 
it looks somehow similar:

For i.MX6 we have the following patch in U-Boot:

http://git.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=commitdiff;h=f2f7745825ee5f6bae5b480c8e9c6641a7ffa73b

If this is the same, maybe we should discuss about (a) where to do this 
(boot loader or kernel) and (b) if we could create a common function for 
this?

Best regards

Dirk