Thread (8 messages) flat view 8 messages, 3 authors, 2013-07-31

RE: [alsa-devel] [PATCH 2/3] ASoC: fsl: Add S/PDIF CPU DAI driver

From: Chen Guangyu-B42378 <hidden>
Date: 2013-07-31 14:12:18
Also in: alsa-devel, linux-devicetree

Hi Lars

Thank you for the sage advices.

I'll revise the patch and send the v2.
________________________________________
From: Lars-Peter Clausen [lars@metafoo.de]
Sent: Wednesday, July 31, 2013 8:16 PM
To: Chen Guangyu-B42378
Cc: broonie@kernel.org; timur@tabi.org; alsa-devel@alsa-project.org; linuxp=
pc-dev@lists.ozlabs.org; devicetree-discuss@lists.ozlabs.org; rob.herring@c=
alxeda.com
Subject: Re: [alsa-devel] [PATCH 2/3] ASoC: fsl: Add S/PDIF CPU DAI driver

[...]
a/Documentation/devicetree/bindings/sound/fsl,spdif.txt
b/Documentation/devicetree/bindings/sound/fsl,spdif.txt
quoted hunk ↗ jump to hunk
new file mode 100644
index 0000000..a655800
--- /dev/null
+++ b/Documentation/devicetree/bindings/sound/fsl,spdif.txt
@@ -0,0 +1,63 @@
+Freescale Sony/Philips Digital Interface Format (S/PDIF) Controller
+
+The Freescale S/PDIF audio block is a stereo transceiver that allows the
+processor to receive and transmit digital audio via an coaxial cable or
+a fibre cable.
+
+Required properties:
+
+  - compatible : Compatible list, contains "fsl,spdif".
That's not what the driver says though.
+
+  - reg : Offset and length of the register set for the device.
+
+  - interrupts : <a b> where a is the interrupt number and b is a field =
that
+    represents an encoding of the sense and level information for the in=
terrupt.
+    This should be encoded based on the information in section 2) depend=
ing on
+    the type of interrupt controller you have.
The exact layout of the cell depends on the parent interrupt controller, so
you probably shouldn't describe it here.
+
+  - clocks : The phandle for the clock ID number registered in clock tre=
e.
+
+  - fsl,spdif-dma-events: The dma event ID numbers for Tx and Rx.
+
Use the generic DMA bindings.
+Optional properties:
+
+  - rx-clk-source : The clock cource for Rx. Need to set this source acc=
ording
+  to the SoC datasheet in SPDIF_SRPC section. If absent, the default sou=
rce is
+  value 0x0 - if (DPLL Locked) SPDIF_RxClk else extal.
+
+  - tx-clk-source : The clock cources for Tx. There're three sources, ea=
ch for
+  different supported sample rate, sequentially 32000Hz, 44100Hz and 480=
00Hz.
+  Need to set this source according to the SoC datasheet in SPDIF_STC se=
ction.
+  If absent, the default source is value 0x1 - CCM spdif0_clk_root input=
.
+
+  - tx-clk-div : The clock divider factor for Tx clock. There're three v=
alues,
+  each for different supported sample rate, sequentially 32000Hz 44100Hz=
 48000Hz.
+  Need to set this source according to the clock rate from the clock sou=
rce.
+  If absent, the default divider factor is <37 23 37> by using spdif0_cl=
k source.

Can't the driver figure out the divider values on its own based on the inpu=
t
clock rate?

- Lars
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