Re: [PATCH 3/3] tpm/tpm_crb: cache cmd_size register value.

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

On Wed, Sep 07, 2016 at 02:32:33PM +0300, Tomas Winkler wrote:
> Instead of expensive register access on retrieving cmd_size
> on each send, save the value during initialization in the private
> context. The value doesn't change.
> 
> Signed-off-by: Tomas Winkler <tomas.winkler-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

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

/Jarkko

> ---
>  drivers/char/tpm/tpm_crb.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> index cf9aab698dfe..f8c9d587029b 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -81,6 +81,7 @@ struct crb_priv {
>  	struct crb_control_area __iomem *cca;
>  	u8 __iomem *cmd;
>  	u8 __iomem *rsp;
> +	u32 cmd_size;
>  };
>  
>  /**
> @@ -217,11 +218,9 @@ static int crb_send(struct tpm_chip *chip, u8 *buf, size_t len)
>  	struct crb_priv *priv = dev_get_drvdata(&chip->dev);
>  	int rc = 0;
>  
> -	if (len > ioread32(&priv->cca->cmd_size)) {
> -		dev_err(&chip->dev,
> -			"invalid command count value %x %zx\n",
> -			(unsigned int) len,
> -			(size_t) ioread32(&priv->cca->cmd_size));
> +	if (len > priv->cmd_size) {
> +		dev_err(&chip->dev, "invalid command count value %zd %d\n",
> +			len, priv->cmd_size);
>  		return -E2BIG;
>  	}
>  
> @@ -374,6 +373,7 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv,
>  		ret = PTR_ERR(priv->cmd);
>  		goto out;
>  	}
> +	priv->cmd_size = cmd_size;
>  
>  	memcpy_fromio(&rsp_pa, &priv->cca->rsp_pa, 8);
>  	rsp_pa = le64_to_cpu(rsp_pa);
> -- 
> 2.7.4
> 

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