[coreboot-gerrit] Change in coreboot[master]: drivers/spi/tpm: Add sleep delay after ready cmd.

[Justin TerAvest (Code Review)]

Justin TerAvest has uploaded this change for review. ( https://review.coreboot.org/25543


Change subject: drivers/spi/tpm: Add sleep delay after ready cmd.
......................................................................

drivers/spi/tpm: Add sleep delay after ready cmd.

This is analogous to a sleep done in the I2C TPM driver to ensure that
cr50 has time to process the COMMAND_READY command before receiving any
later traffic. This change made the TPM much more reliable (though not
perfect).

BUG=b:75306520
BRANCH=None
TEST=Significantly improved reliability

Signed-off-by: Justin TerAvest

Change-Id: Ia25467dc60c968b3b3892e59f90f0393161375c8
---
M src/drivers/spi/tpm/tpm.c
1 file changed, 3 insertions(+), 0 deletions(-)



  git pull ssh://review.coreboot.org:29418/coreboot refs/changes/43/25543/1

diff --git a/src/drivers/spi/tpm/tpm.c b/src/drivers/spi/tpm/tpm.c
index c0fee46..a7900c6 100644
--- a/src/drivers/spi/tpm/tpm.c
+++ b/src/drivers/spi/tpm/tpm.c
@@ -38,6 +38,7 @@
 #define TPM_FW_VER	  (TPM_LOCALITY_0_SPI_BASE + 0xf90)
 
 #define CR50_TIMEOUT_INIT_MS 30000 /* Very long timeout for TPM init */
+#define CR50_SLEEP_LONG 210 /* in usec */
 
 /* SPI slave structure for TPM device. */
 static struct spi_slave g_spi_slave CAR_GLOBAL;
@@ -725,6 +726,8 @@
 
 	/* Move the TPM back to idle state. */
 	write_tpm_sts(TPM_STS_COMMAND_READY);
+	/* Add sleep after sending command ready so TPM has time to process */
+	udelay(CR50_SLEEP_LONG);
 
 	return payload_size;
 }

-- 
To view, visit https://review.coreboot.org/25543
To unsubscribe, or for help writing mail filters, visit https://review.coreboot.org/settings

Gerrit-Project: coreboot
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: Ia25467dc60c968b3b3892e59f90f0393161375c8
Gerrit-Change-Number: 25543
Gerrit-PatchSet: 1
Gerrit-Owner: Justin TerAvest <teravest at chromium.org>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.coreboot.org/pipermail/coreboot-gerrit/attachments/20180405/87f37db0/attachment.html>