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Message-ID: <6e120eee-5cec-460c-87d2-40ef776efc3d@gmail.com>
Date: Tue, 19 Mar 2024 20:02:48 +0200
From: Péter Ujfalusi <peter.ujfalusi@...il.com>
To: Bastien Curutchet <bastien.curutchet@...tlin.com>,
Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>, Jaroslav Kysela <perex@...ex.cz>,
Takashi Iwai <tiwai@...e.com>
Cc: linux-sound@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>, herve.codina@...tlin.com,
christophercordahi@...ometrics.ca
Subject: Re: [PATCH 12/13] ASoC: dt-bindings: davinic-mcbsp: Add the
'ti,drive-dx' property
On 15/03/2024 13:27, Bastien Curutchet wrote:
> McBSP is able to handle capture and playback stream.
> The McBSP's DX pins that outputs serial data during playback streams can
> be used to output a chosen pattern during capture streams. For instance,
> this can be useful to drive an active-low signal during capture streams
> (by choosing <0> as pattern)
or configure the MCBSPx.DX pin as GPO and use it as a GPIO?
Quite novel use of the hardware, no doubt about it. If you don't have
DMA servicing the TX, it will just re-transmit the word from from the
DXR register when the transmitter is pulled out of reset.
Interesting, but I'm not sure if this belongs to DT.
> Add a 'ti,drive-dx' property that can be used to repeatedly output a
> chosen pattern on DX pin while capture stream is ON.
>
> Signed-off-by: Bastien Curutchet <bastien.curutchet@...tlin.com>
> ---
> Documentation/devicetree/bindings/sound/davinci-mcbsp.yaml | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/sound/davinci-mcbsp.yaml b/Documentation/devicetree/bindings/sound/davinci-mcbsp.yaml
> index d8d4e7ea6e02..f4d1fc6bcd61 100644
> --- a/Documentation/devicetree/bindings/sound/davinci-mcbsp.yaml
> +++ b/Documentation/devicetree/bindings/sound/davinci-mcbsp.yaml
> @@ -80,6 +80,13 @@ properties:
> Enable synchronisation error detections when an unexpected frame pulse is
> received. If not present, unexpected frame pulses are ignored.
>
> + ti,drive-dx:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description:
> + If the property is present, McBSP will repeatedly output the selected
> + value on DX pin during capture streams. For instance, if set to 0, this
> + can be used to drive an active-low signal.
> +
> required:
> - "#sound-dai-cells"
> - compatible
--
Péter
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