From 523599c940ba2f1b3ad546ec0094af6d91e71fd9 Mon Sep 17 00:00:00 2001
From: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Date: Fri, 22 Jan 2021 11:19:48 -0500
Subject: drm/amdgpu: Remember to wait 10ms for write buffer flush v2
Git-commit: 2485f8cfff3898cb4dc51470f697775c27075967
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
EEPROM spec requests this.
v2: Only to be done for write data transactions.
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
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 105516603432..fe0e9b0c4d5a 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);
--
2.38.1