[PATCH] [3.3] ARM: tegra: use APB DMA for accessing APB devices

[Stephen Warren]

Olof Johansson wrote at Tuesday, October 18, 2011 12:18 PM:
> From: Jon Mayo <jmayo at nvidia.com>
> 
> Tegra2 hangs if APB registers are accessed from the cpu during an
> apb dma operation. The workaround is to use apb dma to read/write the
> registers instead.
...
> +++ b/arch/arm/mach-tegra/apbio.c
...
> +#ifdef CONFIG_TEGRA_SYSTEM_DMA
...
> +static inline u32 apb_readl(unsigned long offset)
...
> +static inline void apb_writel(u32 value, unsigned long offset)
...
> +#else
> +static inline u32 apb_readl(unsigned long offset)
...
> +static inline void apb_writel(u32 value, unsigned long offset)
...
> +#endif
> +
> +u32 tegra_apb_readl(unsigned long offset)
> +{
> +	return apb_readl(offset);
> +}
> +
> +void tegra_apb_writel(u32 value, unsigned long offset)
> +{
> +	apb_writel(value, offset);
> +}

Why not just make the actual implementations use the exported names, and
have them not be static inline? That way, you avoid the extra function
wrapping them.

> +void tegra_init_apb_dma(void)
> +{
> +#ifdef CONFIG_TEGRA_SYSTEM_DMA
> +	tegra_apb_dma = tegra_dma_allocate_channel(TEGRA_DMA_MODE_ONESHOT |
> +		TEGRA_DMA_SHARED);
> +	if (!tegra_apb_dma) {
> +		pr_err("%s: can not allocate dma channel\n", __func__);

It seems like that should be a lot more noisy if the result is potential
HW hangs. Same for the other error below.

-- 
nvpublic