On 13.01.2016 13:26, Vinod Koul wrote:
On Thu, Jan 07, 2016 at 05:33:01PM +0000, kernel@xxxxxxxxxxxxxxxx wrote:
@@ -638,13 +666,21 @@ static int bcm2835_dma_probe(struct platform_device *pdev)
goto err_no_dma;
}
- for (i = 0; i < pdev->num_resources; i++) {
- irq = platform_get_irq(pdev, i);
+ for (i = 0; i <= BCM2835_DMA_MAX_CHANNEL_NUMBER; i++) {
+ if (BCM2835_DMA_IRQ_SHARED_MASK & BIT(i)) {
Ideally this should be done thru DT data and not hard coded in kernel. I
dont think this assumption will hold good for next gen of this device, so
better to get this from DT!
The ideal solution would be breaking the DT in such a way that we could
define a register range and interrupt per dma-channel looking something
like this:
diff --git a/arch/arm/boot/dts/bcm2835.dtsi b/arch/arm/boot/dts/bcm2835.dtsi
index 83d9787..9526b91 100644
--- a/arch/arm/boot/dts/bcm2835.dtsi
+++ b/arch/arm/boot/dts/bcm2835.dtsi
@@ -31,8 +31,28 @@
dma: dma@7e007000 {
compatible = "brcm,bcm2835-dma";
- reg = <0x7e007000 0xf00>;
- interrupts = <1 16>,
+ reg = <0x7e007f00 0x100>, /* status reg */
+ /* dma channel 0-14 base addresses */
+ <0x7e007000 0x100>,
+ <0x7e007100 0x100>,
+ <0x7e007200 0x100>,
+ <0x7e007300 0x100>,
+ <0x7e007400 0x100>,
+ <0x7e007500 0x100>,
+ <0x7e007600 0x100>,
+ <0x7e007700 0x100>,
+ <0x7e007800 0x100>,
+ <0x7e007900 0x100>,
+ <0x7e007a00 0x100>,
+ <0x7e007b00 0x100>,
+ <0x7e007c00 0x100>,
+ <0x7e007d00 0x100>,
+ <0x7e007e00 0x100>,
+ /* dma channel 15 uses a different base */
+ <0x7ee05000 0x100>;
+ interrupts = <1 28>, /* catch all DMA-interrupts */
+ /* dma channel 0-10 interrupts */
+ <1 16>,
<1 17>,
<1 18>,
<1 19>,
@@ -43,9 +63,30 @@
<1 24>,
<1 25>,
<1 26>,
+ /* dma channel 11-14 share irq */
<1 27>,
- <1 28>;
-
+ <1 27>,
+ <1 27>,
+ <1 27>,
+ /* no irq support for dma channel 15 */
+ < 0 >;
+ dma-names = "shared",
+ "dma0",
+ "dma1",
+ "dma2",
+ "dma3",
+ "dma4",
+ "dma5",
+ "dma6",
+ "dma7",
+ "dma8",
+ "dma9",
+ "dma10",
+ "dma11",
+ "dma12",
+ "dma13",
+ "dma14",
+ "dma15";
#dma-cells = <1>;
brcm,dma-channel-mask = <0x7f35>;
(or similar)
This actually would allow us to make "brcm,dma-channel-mask" redundant,
as we could remove those dma channels that are owned by the firmware
directly from the list.
That way we could also map other capabilities via the DT.
It would also allow a transparent addition of additional dma channels
with newer versions of the HW - mostly - by modifying the DT.
But that would be frowned upon, so I had to come up with the approach
taken, which makes the following assumptions:
* the DT maps only the interrupts that are assigned to the HW block
* the driver knows about the number of DMA channels in HW
* the driver knows about the mapping of shared interrupts
(11-14 share irq).
It is not optimal, but at least it works with the least amount of
change to the DT - and what about all those assumptions that we
would need to hard-code to be backwards compatible to the DT without?
I guess we could replace BCM2835_DMA_MAX_CHANNEL_NUMBER with:
/* we do not support dma channel 15 with this driver */
#define BCM2835_DMA_MAX_CHANNEL_SUPPORTED 14
...
for (i = 0;
i <= min_t(int, flv(chans_available),
BCM2835_DMA_MAX_CHANNEL_SUPPORTED);
i++) {
So which way would you prefer this to go - I got another few days
before I leave on vacation.
Thanks,
Martin
--
To unsubscribe from this list: send the line "unsubscribe dmaengine" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
