[PATCH] [REPOST] tpm: suppress durations sysfs output if not read

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

Suppress the output in the 'durations' sysfs entry if they were not read
during driver initialization. This is similar to other sysfs entries
that return nothing if for some reason sending the commands to the TPM
fails.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

---
 drivers/char/tpm/tpm.c |    3 +++
 1 file changed, 3 insertions(+)

Index: linux-2.6/drivers/char/tpm/tpm.c
===================================================================
--- linux-2.6.orig/drivers/char/tpm/tpm.c
+++ linux-2.6/drivers/char/tpm/tpm.c
@@ -963,6 +963,9 @@ ssize_t tpm_show_durations(struct device
 {
 	struct tpm_chip *chip = dev_get_drvdata(dev);
 
+	if (chip->vendor.duration[TPM_LONG] == 0)
+		return 0;
+
 	return sprintf(buf, "%d %d %d [%s]\n",
 		       jiffies_to_usecs(chip->vendor.duration[TPM_SHORT]),
 		       jiffies_to_usecs(chip->vendor.duration[TPM_MEDIUM]),