> -----Original Message----- > From: Rob Herring <robh+dt@xxxxxxxxxx> > Sent: 04 February 2023 01:20 > To: Krishna Yarlagadda <kyarlagadda@xxxxxxxxxx> > Cc: broonie@xxxxxxxxxx; peterhuewe@xxxxxx; jgg@xxxxxxxx; > jarkko@xxxxxxxxxx; krzysztof.kozlowski+dt@xxxxxxxxxx; linux- > spi@xxxxxxxxxxxxxxx; linux-tegra@xxxxxxxxxxxxxxx; linux- > integrity@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > thierry.reding@xxxxxxxxx; Jonathan Hunter <jonathanh@xxxxxxxxxx>; > Sowjanya Komatineni <skomatineni@xxxxxxxxxx>; Laxman Dewangan > <ldewangan@xxxxxxxxxx> > Subject: Re: [Patch V2 3/4] spi: dt-bindings: Add Tegra TPM wait polling flag > > External email: Use caution opening links or attachments > > > On Fri, Feb 3, 2023 at 7:02 AM Krishna Yarlagadda > <kyarlagadda@xxxxxxxxxx> wrote: > > > > Add "nvidia,wait-polling" flag to enable TCG TIS hardware flow control. > > Tell me something that the diff doesn't. > > > > > Signed-off-by: Krishna Yarlagadda <kyarlagadda@xxxxxxxxxx> > > --- > > .../bindings/spi/nvidia,tegra210-quad-peripheral-props.yaml | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad- > peripheral-props.yaml > b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad-peripheral- > props.yaml > > index 2c3cada75339..19d2b30cadbf 100644 > > --- a/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad- > peripheral-props.yaml > > +++ b/Documentation/devicetree/bindings/spi/nvidia,tegra210-quad- > peripheral-props.yaml > > @@ -29,4 +29,10 @@ properties: > > minimum: 0 > > maximum: 255 > > > > + nvidia,wait-polling: > > + description: > > + Enable TPM wait polling feature for QSPI as specified in TCG PC Client > > + Specific TPM Interface Specification (TIS). > > + $ref: /schemas/types.yaml#/definitions/flag > > Why do you need this flag when you have a compatible that also > indicates you have a quirk. > > If this a TPM feature, why is it enabled for every single SPI slave device? > > If the fundamental issue is the controller only supports half-duplex, > why can't you just check that from the driver? Can't the SPI subsystem > tell you that the host controller is half-duplex? Though sometimes > that may be board level property I suppose. If so, define the h/w > quirk, not the driver mode in DT. Half-duplex is probably something > everyone could use, not just Nvidia. > > Please discuss this series internally with the folks you marked as > maintainers. It has issues I'm sure they would have also pointed out. > > Rob QSPI is a multi-chip-select controller and HW wait polling is only for TPM Both controller and device would need a flag/setting to identify support for this feature. Using SPI controller flags and SPI device mode flags to avoid device tree flags. Moved HW/alternate TPM flow control into existing driver. No need of new compatible now. KY
