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BeagleBone Black REV(C) hdmi 输出?

现在用的是 SDK7.0

dts : am335x-boneblack.dts

现在 hdmi 口有视频输出,启动的时候可以看到。

但如果要使用 hdmi 音频驱动应该要怎么做?

在内核配置里我的配置选了: 

 <*> Sound card support  —>

            <*>   Advanced Linux Sound Architecture  —>

— Advanced Linux Sound Architecture                                                              │ │  
  │ │                            < >   Sequencer support                                                                            │ │  
  │ │                            <M>   OSS Mixer API                                                                                │ │  
  │ │                            <M>   OSS PCM (digital audio) API                                                                  │ │  
  │ │                            [*]     OSS PCM (digital audio) API – Include plugin system                                        │ │  
  │ │                            < >   HR-timer backend support                                                                     │ │  
  │ │                            [ ]   Dynamic device file minor numbers                                                            │ │  
  │ │                            [*]   Support old ALSA API                                                                         │ │  
  │ │                            [*]   Verbose procfs contents                                                                      │ │  
  │ │                            [*]   Verbose printk                                                                               │ │  
  │ │                            [*]   Debug                                                                                        │ │  
  │ │                            [ ]     More verbose debug                                                                         │ │  
  │ │                            [ ]     Enable PCM ring buffer overrun/underrun debugging                                          │ │  
  │ │                            [*]   Generic sound devices  —>                                                                  │ │  
  │ │                            [*]   PCI sound devices  —>                                                                      │ │  
  │ │                            [*]   ARM sound devices  —-                                                                      │ │  
  │ │                            [*]   SPI sound devices  —-                                                                      │ │  
  │ │                            [*]   USB sound devices  —>                                                                      │ │  
  │ │                            <*>   ALSA for SoC audio support  —>                                                             │ │  
  │ │                                                                      

— ALSA for SoC audio support                                                                     │ │  
  │ │                            < >   SoC Audio for the Atmel System-on-Chip                                                       │ │  
  │ │                            <*>   SoC Audio for TI DAVINCI or AM33XX/AM43XX chips                                              │ │  
  │ │                            <*>   SoC Audio for the AM33XX chip based boards                                                   │ │  
  │ │                            <M>   SoC Audio for the AM43XX and TLV320AIC3111 based board                                       │ │  
  │ │                            <M>   Synopsys I2S Device Driver                                                                   │ │  
  │ │                            <*>   SoC Audio for the Texas Instruments OMAP chips                                               │ │  
  │ │                            < >   SoC Audio support for Nokia N810                                                             │ │  
  │ │                            < >   SoC Audio support for Nokia RX-51                                                            │ │  
  │ │                            < >   SoC Audio support for OMAP3517 / AM3517 EVM                                                  │ │  
  │ │                            <M>   SoC Audio support for DRA7 EVM                                                               │ │  
  │ │                            <M>   SoC Audio support for TI SoC based boards with twl4030 codec                                 │ │  
  │ │                            <M>   SoC Audio support for OMAP boards using ABE and twl6040 codec                                │ │  
  │ │                            <*>   SoC Audio support for Texas Instruments OMAP HDMI                                            │ │  
  │ │                            <M>   SoC Audio support for OMAP3 Pandora                                                          │ │  
  │ │                            <*>   ASoC Simple sound card support    

  但系统加载后 没有 相关 alsa 声卡,

还要做 Device tree?

Jian Zhou:

HDMI不是高清输出吗?怎么还有音频驱动呢?

jing zhu:

回复 Jian Zhou:

我看到 BeagleBone Black 的 TRM 上有说有 HDMI Audio 的?

Steven Liu1:

回复 jing zhu:

HDMI是可以传音频的,BBB上的设计,是通过McASP0的设置来输出音频I2S,然后由TDA19988转成HDMI输出。

这块的设计是新加入的,BBB上第一次出现,没具体玩过。不过建议你可以查看一下,当前是否使能了McASP0的相关设置,如果是连Pinmux都没做的话,肯定是没配好了。

jing zhu:

回复 Steven Liu1:

uart0: serial@44e09000 {            pinctrl-names = "default";            pinctrl-0 = <&uart0_pins>;            status = "okay";        };

uart0_pins: pinmux_uart0_pins {            pinctrl-single,pins = <                0x170 (PIN_INPUT_PULLUP | MUX_MODE0)    /* uart0_rxd.uart0_rxd */                0x174 (PIN_OUTPUT_PULLDOWN | MUX_MODE0)    /* uart0_txd.uart0_txd */            >;        };

上面是摘自 SDK7.0 am335x-bone-common.dtsi

你好,有没有文章讲解 device tree 的呢? 基础一点的,比如,我想知道 那个0x170 是怎么决定的,可以通过哪个手册,的什么方法可以查到。

44e09000 这个地址我在 am335x 技术手册 system map 里按到了,但下面那个 0x170, 0x174 网上说是个偏移值,但我没有找到. 这方面我还

比较菜,请谅解.

Steven Liu1:

回复 jing zhu:

前面的44e09000代表的是UART0的基地址,这个可以从system map中翻到。

下面的0x170,0x174是对于Control module内的设置pinmux寄存器的地址偏移量,其基址为0x44e10800。

举个例子,如0x170,实际指代的地址是0x44e10800+0x170=0x44e10970,对照TRM的地9章control module,你可以看到这个寄存器就是对uart0_rxd这个管脚的配置信息。

谷歌度娘上搜一下device tree吧,还是能看到不少介绍的。

Steven Liu1:

回复 jing zhu:

刚才查了beagleboneblack的dts配置,里面没有对mcasp0进行初始化,这块的功能应该是只做了接线,并没有使能相应的功能,需要你自己添加。

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