Hey Tejun Heo,
On 04-12-13 13:32, Tejun Heo wrote:
On Wed, Dec 04, 2013 at 01:10:53PM +0100, oliver@xxxxxxxxxxx wrote:
From: Oliver Schinagl <oliver@xxxxxxxxxxx>
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@xxxxxxxxxxx>
---
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?
I have no idea why Allwinner added that and what it really does. We have
no documentation, only code drops.
I had high hopes someone around here knows what it could mean and where
it does belong.
+
/* 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?
Again, I don't know, this is where Allwinner had put it. We don't even
know who's IP they use. I'm happy to start experimenting moving this
around a bit and will take your clue to figure out what you mean and if
it could work.
Oliver
Thanks.
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