drm/amdgpu: Remember to wait 10ms for write buffer flush v2

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>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c
index 1055166..fe0e9b0 100644 (file)
--- 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);