From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: * X-Spam-Status: No, score=1.1 required=5.0 tests=DATE_IN_PAST_06_12 autolearn=no autolearn_force=no version=3.4.4 Received: (qmail 3371 invoked from network); 25 Apr 2021 22:44:57 -0000 Received: from 1ess.inri.net (216.126.196.35) by inbox.vuxu.org with ESMTPUTF8; 25 Apr 2021 22:44:57 -0000 Received: from duke.felloff.net ([216.126.196.34]) by 1ess; Sun Apr 25 12:07:54 -0400 2021 Message-ID: <0C73F8031AC040C9C98E26332A9A4D2B@felloff.net> Date: Sun, 25 Apr 2021 18:07:43 +0200 From: cinap_lenrek@felloff.net To: 9front@9front.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit List-ID: <9front.9front.org> List-Help: X-Glyph: ➈ X-Bullshit: lossless immutable proxy SQL just-in-time map/reduce-aware controller Subject: Re: [9front] Getting Started with Kernel Development? Reply-To: 9front@9front.org Precedence: bulk > I've also got the "BCM2835 ARM Peripherals" spec, which specifies how > to interact with the chip's I2S audio interface. As far as i know, the stock raspberry pi is not using I2S. There are some people that have build their own soundcards for the pi with a I2S DAC but it is not standard. Instead, they hacked together some filter circuit and connected it to a GPIO pin. (This pattern is a logical continuation on raspberry pi hardware design philosphy, where using the existing dedicated peripherals for their intended purpose must be rejected and standards must be ignored: cpu -> GPU, ethernet -> USB, audio -> GPIO, wifi -> SDCARD, usb -> ?????WHATISTHIS????, usbc -> ?????, PXE -> ???????). The GPU has firmware code to drive that GPIO pin and also send audio over HDMI, but todo that you have to talk to the videocore firmware thru a complicated software media streaming interface. Afik, it is possible to drive the gpio pin from the cpu somehow but quality will be garbage and waste alot of power. -- cinap