linux-kernel - Re: [PATCH v2 4/8] dt-bindings: serial: Add support for selecting data transfer mode

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Message-ID: <dudqd2y42wy6iq2k73aphd5ol4mtq7z4c54zhd27rl745rrw5x@p3oummf2jke7>
Date: Mon, 27 Jan 2025 16:27:07 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Viken Dadhaniya <quic_vdadhani@...cinc.com>, andi.shyti@...nel.org, 
	robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	gregkh@...uxfoundation.org, jirislaby@...nel.org, broonie@...nel.or, andersson@...nel.org, 
	konradybcio@...nel.org, johan+linaro@...nel.org, dianders@...omium.org, 
	agross@...nel.org, linux-arm-msm@...r.kernel.org, linux-i2c@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org, 
	linux-spi@...r.kernel.org, quic_msavaliy@...cinc.com, quic_anupkulk@...cinc.com
Subject: Re: [PATCH v2 4/8] dt-bindings: serial: Add support for selecting
 data transfer mode

On Mon, Jan 27, 2025 at 08:02:12AM +0100, Krzysztof Kozlowski wrote:
> On 24/01/2025 11:53, Viken Dadhaniya wrote:
> > Data transfer mode is fixed by TrustZone (TZ), which currently restricts
> > developers from modifying the transfer mode from the APPS side.
> > 
> > Document the 'qcom,xfer-mode' properties to select the data transfer mode,
> > either GPI DMA (Generic Packet Interface) or non-GPI mode (PIO/CPU DMA).
> > 
> > UART controller can operate in one of two modes based on the
> > 'qcom,xfer-mode' property, and the firmware is loaded accordingly.
> > 
> > Co-developed-by: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
> > Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
> > Signed-off-by: Viken Dadhaniya <quic_vdadhani@...cinc.com>
> > ---
> > 
> > v1 -> v2:
> > 
> > - Drop 'qcom,load-firmware' property and add 'firmware-name' property in
> >   qup common driver.
> > - Update commit log.
> > 
> > v1 Link: https://lore.kernel.org/linux-kernel/20241204150326.1470749-4-quic_vdadhani@quicinc.com/
> > ---
> > ---
> >  .../devicetree/bindings/serial/qcom,serial-geni-qcom.yaml | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/serial/qcom,serial-geni-qcom.yaml b/Documentation/devicetree/bindings/serial/qcom,serial-geni-qcom.yaml
> > index dd33794b3534..383773b32e47 100644
> > --- a/Documentation/devicetree/bindings/serial/qcom,serial-geni-qcom.yaml
> > +++ b/Documentation/devicetree/bindings/serial/qcom,serial-geni-qcom.yaml
> > @@ -56,6 +56,13 @@ properties:
> >    reg:
> >      maxItems: 1
> >  
> > +  qcom,xfer-mode:
> > +    description: Set the value to 1 for non-GPI (FIFO/CPU DMA) mode and 3 for GPI DMA mode.
> > +      The default mode is FIFO.
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    enum: [1, 3]
> > +
> > +
> 
> Just one blank line, but anyway, this property should not be in three
> places. Do you really expect that each of serial engines within one
> GeniQUP will be configured differently by TZ?

Yes, each SE is configured separately and it's quite frequent when
different SEs have different DMA configuration.

-- 
With best wishes
Dmitry