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SubjectRe: [PATCH 1/3] RFC: AHCI: libahci is missing DMA
On Wed, Dec 04, 2013 at 01:10:53PM +0100, oliver@schinagl.nl wrote:
> From: Oliver Schinagl <oliver@schinagl.nl>
>
> The Allwinner sunxi platforms have patched in the following to enable
> DMA. This patch enables DMA controllers for the SUNXI Architecture.
>
> Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>
> ---
> drivers/ata/ahci.h | 6 ++++++
> drivers/ata/libahci.c | 8 ++++++++
> 2 files changed, 14 insertions(+)
>
> diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
> index 2289efdf..2bf2423 100644
> --- a/drivers/ata/ahci.h
> +++ b/drivers/ata/ahci.h
> @@ -138,6 +138,7 @@ enum {
> PORT_SCR_NTF = 0x3c, /* SATA phy register: SNotification */
> PORT_FBS = 0x40, /* FIS-based Switching */
> PORT_DEVSLP = 0x44, /* device sleep */
> + PORT_DMA = 0x70, /* direct memory access */
>
> /* PORT_IRQ_{STAT,MASK} bits */
> PORT_IRQ_COLD_PRES = (1 << 31), /* cold presence detect */
> @@ -209,6 +210,11 @@ enum {
> PORT_DEVSLP_DSP = (1 << 1), /* DevSlp present */
> PORT_DEVSLP_ADSE = (1 << 0), /* Aggressive DevSlp enable */
>
> + /* PORT_DMA bits */
> + PORT_DMA_SETUP_OFFSET = 8, /* dma setup offset */
> + PORT_DMA_SETUP_MASK = (0xff << PORT_DMA_SETUP_OFFSET),/* dma mask */
> + PORT_DMA_SETUP_INIT = (0x44 << 0),

Ummm... this doesn't belong to ahci proper, right?

> +
> /* hpriv->flags bits */
>
> #define AHCI_HFLAGS(flags) .private_data = (void *)(flags)
> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index c482f8c..d697a74 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -570,6 +570,14 @@ void ahci_start_engine(struct ata_port *ap)
> void __iomem *port_mmio = ahci_port_base(ap);
> u32 tmp;
>
> +#ifdef CONFIG_ARCH_SUNXI
> + /* Setup DMA before DMA start */
> + tmp = readl(port_mmio + PORT_DMA);
> + tmp &= ~PORT_DMA_SETUP_MASK;
> + tmp |= PORT_DMA_SETUP_INIT << PORT_DMA_SETUP_OFFSET;
> + writel(tmp, port_mmio + PORT_DMA);
> +#endif

If this is something platform device specific, wouldn't overriding
->port_start() which wraps around ahci_port_start() make more sense?

Thanks.

--
tejun


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