[PATCH 12/40] drm/amdgpu: Remember to wait 10ms for write buffer flush v2

[Luben Tuikov]

From: Andrey Grodzovsky <andrey.grodzovsky at amd.com>

EEPROM spec requests this.

v2: Only to be done for write data transactions.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Reviewed-by: Luben Tuikov <luben.tuikov at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c
index 10551660343278..fe0e9b0c4d5a38 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c
@@ -55,6 +55,21 @@ int amdgpu_eeprom_xfer(struct i2c_adapter *i2c_adap,
 		r = i2c_transfer(i2c_adap, msgs, ARRAY_SIZE(msgs));
 		if (r <= 0)
 			return r;
+
+		/* Only for write data */
+		if (!msgs[1].flags)
+			/*
+			 * According to EEPROM spec there is a MAX of 10 ms required for
+			 * EEPROM to flush internal RX buffer after STOP was issued at the
+			 * end of write transaction. During this time the EEPROM will not be
+			 * responsive to any more commands - so wait a bit more.
+			 *
+			 * TODO Improve to wait for first ACK for slave address after
+			 * internal write cycle done.
+			 */
+			msleep(10);
+
+
 		bytes_transferred = r - EEPROM_OFFSET_LENGTH;
 		eeprom_addr += bytes_transferred;
 		msgs[0].buf[0] = ((eeprom_addr >> 8) & 0xff);
-- 
2.32.0