Thread (14 messages) 14 messages, 3 authors, 2015-03-04
STALE4105d

[PATCH 2/4] ARM: mvebu: add audio I2S controller to Armada 38x Device Tree

From: Marcin Wojtas <hidden>
Date: 2015-02-26 09:05:08
Also in: alsa-devel

2015-02-26 1:30 GMT+01:00 Sebastian Hesselbarth
[off-list ref]:
On 26.02.2015 01:11, Marcin Wojtas wrote:
quoted
2015-02-25 23:21 GMT+01:00 Sebastian Hesselbarth
[off-list ref]:
quoted
On 25.02.2015 22:58, Marcin Wojtas wrote:
[...]
quoted
quoted
sorry but NACK. The PLL and SoC ctrl are not even close to the audio
controller registers.
quoted
+                               interrupts = <GIC_SPI 75
IRQ_TYPE_LEVEL_HIGH>;
+                               clocks = <&gateclk 0>;
+                               clock-names = "internal";


How about providing access to audio PLL by a clock driver and amend the
binding to allow for a second more precise PLL clock, e.g.

         clocks = <&gateclk CLK_AUDIO>, <&pll PLL_AUDIO>;
         clock-names = "internal", "pll";
Good idea. Would you suggest some name for the new driver? How about
clk-audio.c under drivers/clk/mvebu?

Depends on how much you know about the surrounding registers.

If there is more clock related stuff than the audio pll, I'd
suggest to have a single driver for everything that isn't core clk
or clk gates which are already dealt with in the existing driver.

Given that this PLL layout is most likely 38x specific, I'd just put it
into drivers/clk/mvebu/armada-38x.c.
Audio PLL setting consist of 3 independent registers. Adjacent to them
there are same regs for setting TDM PLL, however I doubt  telephony is
going to be supported in foreseeable future (if ever). I also have
strong suspicion that it looks the same in a39x - Thomas, can you take
a look into spec and confirm?
quoted
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we already check for an "extclk" on Dove for the same reason but the
name might be misleading here.

Also, i2c/spdif muxing option could be handled by 38x's pinctrl driver,
we have the same for Dove's internal i2c mux.

If you want to use i2s you just add the option to the default pinctrl
hog:

         pinctrl-0 = <&i2s_pins &audio_mux_i2s>;
         pinctrl-names = "default";
Ok, I'll try to extend pinctrl-armada-38x then.

IMHO, adding a "syscon" compatible to the system-controller node should
do the trick. You can reference the regmap from 38x's pinctrl driver and
have a specific callback for the i2s/spdif muxing. The reg property
range of the system-controller should be extended but that definitely
depends on what the you or the Free Electron guys know about the
register set.
For muxing i2s/spdif (exactly the same pins, they have to be either
way set to "audio" by pinctrl driver) changing single bit in "system
control 1" register is needed. However currently unused, it is already
a part of system-controller at 18200 regmap. Anyway the will of using
either i2s or spdif has to be explicitly represented in DT.

Marcin
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