Re: [PATCH] ARM: davinci: Add the clock for the CPPI 4.1 DMA engine

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On 04/04/2017 08:16 AM, Sekhar Nori wrote:
On Wednesday 29 March 2017 09:39 PM, Alexandre Bailon wrote:
The CPPI 4.1 DMA is sharing its clock with the USB OTG,
and most of the time, the clock will be enabled by USB.
But during the init of the DMA, USB is not enabled (waiting for DMA),
and then we must enable the clock before to do anything.
Add the clock for the CPPI 4.1 DMA engine.

Note:
This patch is to apply instead of:
"ARM: davinci: Make the usb20 clock available to PM runtime"
Okay, but I still liked the fact that that patch was using NULL as
con_id for MUSB clock. That makes sense because MUSB gets a single clock
input. I think you should still make that change. If not for v4.12, then
for v4.13.

Signed-off-by: Alexandre Bailon <abailon@xxxxxxxxxxxx>
---
  arch/arm/mach-davinci/da830.c    | 1 +
  arch/arm/mach-davinci/da850.c    | 1 +
  arch/arm/mach-davinci/da8xx-dt.c | 2 ++
  3 files changed, 4 insertions(+)

diff --git a/arch/arm/mach-davinci/da830.c b/arch/arm/mach-davinci/da830.c
index 073c458..ae4a8a5 100644
--- a/arch/arm/mach-davinci/da830.c
+++ b/arch/arm/mach-davinci/da830.c
@@ -413,6 +413,7 @@ static struct clk_lookup da830_clks[] = {
  	CLK("davinci-mcasp.1",	NULL,		&mcasp1_clk),
  	CLK("davinci-mcasp.2",	NULL,		&mcasp2_clk),
  	CLK("musb-da8xx",	"usb20",	&usb20_clk),
+	CLK("cppi41-dmaengine",	NULL,		&usb20_clk),
Did you try reading /sys/kernel/debug/davinci_clocks after this patch?
It will hang because of the loop created here.
I have tried and I did not get any issues.

Looks like what you want is cppi4.1 dma clock to be a child of MUSB
clock. That way, even if DMA is enabled before MUSB, it still works.
OK. I will update the patch to make cppi4.1 clock a child of usb clock.

Thanks,
Sekhar
Thanks,
Alexandre
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