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SubjectRe: [PATCH 1/3] RFC: AHCI: libahci is missing DMA

On 04-12-13 13:47, Sergei Shtylyov wrote:
> Hello.
>
> On 04-12-2013 16:10, 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
> [...]
>> @@ -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),
>
> Why not shift it right by PORT_DMA_SETUP_OFFSET if you do it in the
> next file anyway?
Verbosity and clarity I suppose, try to reduce the number of magic
values. I don't know what the preferred way is as we know so little
about the IP.
>
> [...]
>> 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
>> +
>
> I don't think #ifdef is appropriate here.
It's not, but I was hoping Smarter devs then me would point me the right
way ;)

Oliver
>
> WBR, Sergei
>



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