[PATCH] cros_ec_i2c: prevent i2c timeout for EC_CMD_FLASH_ERASE

From: Wei-Ning Huang
Date: Mon May 15 2017 - 11:57:56 EST


Some EC chip has larger flash sector size which requires longer erase
time. During erase the CPU is usually stalled and can't even respond to
interrupts. We sleep a while to block any EC command from executing
during the flash erase period.

Signed-off-by: Wei-Ning Huang <wnhuang@xxxxxxxxxx>
---
drivers/mfd/cros_ec_i2c.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

diff --git a/drivers/mfd/cros_ec_i2c.c b/drivers/mfd/cros_ec_i2c.c
index 9f70de1e4c70..8f23d5a8cc5b 100644
--- a/drivers/mfd/cros_ec_i2c.c
+++ b/drivers/mfd/cros_ec_i2c.c
@@ -23,6 +23,14 @@
#include <linux/platform_device.h>
#include <linux/slab.h>

+/*
+ * Some EC chip has larger flash sector size which requires longer erase time.
+ * During erase the CPU is usually stalled and can't even respond to
+ * interrupts. We sleep for a while to block any EC command from executing
+ * during the flash erase period to prevent i2c timeout.
+ */
+#define EC_FLASH_ERASE_DELAY_MS 5000
+
/**
* Request format for protocol v3
* byte 0 0xda (EC_COMMAND_PROTOCOL_3)
@@ -177,6 +185,16 @@ static int cros_ec_pkt_xfer_i2c(struct cros_ec_device *ec_dev,

ret = ec_response->data_len;

+ /*
+ * If we get EC_RES_IN_PROGRESS for EC_CMD_FLASH_ERASE this means EC
+ * need a long time to erase flash, during flash erase CPU is stalled
+ * and can't respond to interrupts, so we sleep for a while to stop new
+ * EC commands from communicating with EC.
+ */
+ if (msg->command == EC_CMD_FLASH_ERASE &&
+ msg->result == EC_RES_IN_PROGRESS)
+ msleep(EC_FLASH_ERASE_DELAY_MS);
+
done:
if (msg->command == EC_CMD_REBOOT_EC)
msleep(EC_REBOOT_DELAY_MS);
--
2.12.2