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

Dmitry Baryshkov
2025-01-27T14:27:12Z

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@quicinc.com>
> > Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
> > Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.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