On 10/19/2015 05:22 AM, Jon Hunter wrote:
On 16/10/15 17:09, Stephen Warren wrote:
On 10/16/2015 01:35 AM, Jon Hunter wrote:
Add device-tree binding documentation for the Tegra210 Audio DMA
controller.
diff --git a/Documentation/devicetree/bindings/dma/tegra210-adma.txt
b/Documentation/devicetree/bindings/dma/tegra210-adma.txt
+Required properties:
+- interrupt-parent: Phandle to the interrupt parent controller.
Nit: Since that is more of a "system level"/standard property, it's
typical not to document it. The property is not actually required if the
inherited value is already correct. Still, it's obvious enough what this
means, so I'd only suggest fixing this if you have to respin for some
other reason.
Ok.
+- clocks: Must contain one entry for the ADMA module clock, "adma_ape".
+- clock-names: Must contain the entry "adma_ape".
Which clock is this in the CAR? I don't see any adma_ape clock
documented in the TRM.
Darn. I thought I had checked this. Yes it should be the AHUB clock and
looking at the current t210 clock patches for mainline this is
TEGRA210_CLK_D_AUDIO. Ok will fix this.
Is there a dedicated reset signal for this module? If so, we should
require a resets property.
No there does not appear to be. Looking at the documentation the ADMA
would be reset by the main APE reset. Seems to be one reset that resets
most modules in the APE.
That raises another issue, the ADMA is in the audio power partition and
currently our downstream driver assumes that this is on. I should at
least check this.
IIRC the situation downstream w.r.t. the audio power partition is
something like:
The AGIC is in that power partition. The Linux kernel AGIC driver gets
probed before the power domain driver for that domain. (I think)
deferred probe doesn't work for the AGIC driver for some reason (perhaps
this is just a bug or oversight in our downstream AGIC driver?). So, the
AGIC driver can't turn on the audio power domain. So, there's a hack in
the bootloader to turn the power domain on. So, everything in the kernel
assumes that power domain is on at boot and so drivers don't have to
explicitly control/request that power domain.
We should fix this properly so that upstream doesn't make the assumption
that the audio power domain is magically on before the kernel boots.
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