Re: [PATCH 2/3] tmp/tpm_crb: fix Intel PTT hw bug during idle state

[Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Wed, Sep 07, 2016 at 02:32:32PM +0300, Tomas Winkler wrote:
> There is a HW bug in Skylake, Kabylake, and Broxton PCH Intel PTT device,
> where most of the registers in the control area except START, REQUEST,
> CANCEL, and LOC_CTRL lost retention when the device is in the idle state.
> Hence we need to bring the device to ready state before accessing the
> other registers. The fix brings device to ready state before trying to read
> command and response buffer addresses in order to remap the for access.
> 
> Signed-off-by: Tomas Winkler <tomas.winkler-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

I think I would add the dev_dbg line permanently with it that you have
in responses in this thread. There's been some unrelated bugs before
where this information in klog would have been very handy.

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>

/Jarkko

> ---
>  drivers/char/tpm/tpm_crb.c | 37 +++++++++++++++++++++++++++----------
>  1 file changed, 27 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> index 98a7fdfe9936..cf9aab698dfe 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -328,6 +328,7 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv,
>  	struct list_head resources;
>  	struct resource io_res;
>  	struct device *dev = &device->dev;
> +	u32 pa_high, pa_low;
>  	u64 cmd_pa;
>  	u32 cmd_size;
>  	u64 rsp_pa;
> @@ -335,15 +336,14 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv,
>  	int ret;
>  
>  	INIT_LIST_HEAD(&resources);
> -	ret = acpi_dev_get_resources(device, &resources, crb_check_resource,
> -				     &io_res);
> +	ret = acpi_dev_get_resources(device, &resources,
> +				     crb_check_resource, &io_res);
>  	if (ret < 0)
>  		return ret;
>  	acpi_dev_free_resource_list(&resources);
>  
>  	if (resource_type(&io_res) != IORESOURCE_MEM) {
> -		dev_err(dev,
> -			FW_BUG "TPM2 ACPI table does not define a memory resource\n");
> +		dev_err(dev, FW_BUG "TPM2 ACPI table does not define a memory resource\n");
>  		return -EINVAL;
>  	}
>  
> @@ -356,12 +356,24 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv,
>  	if (IS_ERR(priv->cca))
>  		return PTR_ERR(priv->cca);
>  
> -	cmd_pa = ((u64) ioread32(&priv->cca->cmd_pa_high) << 32) |
> -		  (u64) ioread32(&priv->cca->cmd_pa_low);
> +	/*
> +	 * PTT HW bug w/a: wake up the device to access
> +	 * possibly not retained registers.
> +	 */
> +	ret = __crb_cmd_ready(dev, priv);
> +	if (ret)
> +		return ret;
> +
> +	pa_high = ioread32(&priv->cca->cmd_pa_high);
> +	pa_low  = ioread32(&priv->cca->cmd_pa_low);
> +	cmd_pa = ((u64)pa_high << 32) | pa_low;
>  	cmd_size = ioread32(&priv->cca->cmd_size);
> +
>  	priv->cmd = crb_map_res(dev, priv, &io_res, cmd_pa, cmd_size);
> -	if (IS_ERR(priv->cmd))
> -		return PTR_ERR(priv->cmd);
> +	if (IS_ERR(priv->cmd)) {
> +		ret = PTR_ERR(priv->cmd);
> +		goto out;
> +	}
>  
>  	memcpy_fromio(&rsp_pa, &priv->cca->rsp_pa, 8);
>  	rsp_pa = le64_to_cpu(rsp_pa);
> @@ -369,7 +381,8 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv,
>  
>  	if (cmd_pa != rsp_pa) {
>  		priv->rsp = crb_map_res(dev, priv, &io_res, rsp_pa, rsp_size);
> -		return PTR_ERR_OR_ZERO(priv->rsp);
> +		ret = PTR_ERR_OR_ZERO(priv->rsp);
> +		goto out;
>  	}
>  
>  	/* According to the PTP specification, overlapping command and response
> @@ -377,10 +390,14 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv,
>  	 */
>  	if (cmd_size != rsp_size) {
>  		dev_err(dev, FW_BUG "overlapping command and response buffer sizes are not identical");
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto out;
>  	}
>  
>  	priv->rsp = priv->cmd;
> +
> +out:
> +	__crb_go_idle(dev, priv);
>  	return 0;
>  }
>  
> -- 
> 2.7.4
> 

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