linux-kernel - Re: [Patch V6 2/3] tpm_tis-spi: Support hardware wait polling

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Date:   Wed, 1 Mar 2023 14:37:45 +0100
From:   Thierry Reding <thierry.reding@...il.com>
To:     Krishna Yarlagadda <kyarlagadda@...dia.com>
Cc:     robh+dt@...nel.org, broonie@...nel.org, peterhuewe@....de,
        jgg@...pe.ca, jarkko@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        linux-spi@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        jonathanh@...dia.com, skomatineni@...dia.com, ldewangan@...dia.com
Subject: Re: [Patch V6 2/3] tpm_tis-spi: Support hardware wait polling

On Mon, Feb 27, 2023 at 10:51:07PM +0530, Krishna Yarlagadda wrote:
[...]
> diff --git a/drivers/char/tpm/tpm_tis_spi_main.c b/drivers/char/tpm/tpm_tis_spi_main.c
[...]
> @@ -140,6 +206,28 @@ int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
>  	return ret;
>  }
>  
> +int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
> +			 u8 *in, const u8 *out)
> +{
> +	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
> +	struct spi_controller *ctlr = phy->spi_device->controller;
> +
> +	/*
> +	 * TPM flow control over SPI requires full duplex support.
> +	 * Send entire message to a half duplex controller to handle
> +	 * wait polling in controller.
> +	 * Set TPM HW flow control flag..
> +	 */
> +	if (ctlr->flags & SPI_CONTROLLER_HALF_DUPLEX) {
> +		phy->spi_device->mode |= SPI_TPM_HW_FLOW;

Can this be pushed up to tpm_tis_spi_probe()? The SPI controller flags
are fixed, so this isn't going to change at runtime, is it?

Thierry

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