From df5238c598e04f6d638b878f8090f985b869932b Mon Sep 17 00:00:00 2001
From: Michael Hanselmann <public@hansmi.ch>
Date: Fri, 24 Dec 2021 17:10:14 +0100
Subject: [PATCH] waveshare2in13v2: Enable hardware early

Enable the clock and analog parts when configuring the mode. In probably
all use cases a drawing operation is following soon after anyway.
Putting the device to sleep disables these hardware parts again.
---
 waveshare2in13v2/controller.go      | 13 ++++---------
 waveshare2in13v2/controller_test.go |  2 ++
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/waveshare2in13v2/controller.go b/waveshare2in13v2/controller.go
index adcb53a..cd65897 100644
--- a/waveshare2in13v2/controller.go
+++ b/waveshare2in13v2/controller.go
@@ -66,16 +66,11 @@ func configDisplayMode(ctrl controller, mode PartialUpdate, lut LUT) {
 	ctrl.sendCommand(writeDisplayOptionRegister)
 	ctrl.sendData([]byte{0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00})
 
-	if mode == Partial {
-		ctrl.sendCommand(displayUpdateControl2)
-		ctrl.sendData([]byte{
-			displayUpdateEnableClock |
-				displayUpdateEnableAnalog,
-		})
-
-		ctrl.sendCommand(masterActivation)
-	}
+	// Start up the parts likely used by a draw operation soon.
+	ctrl.sendCommand(displayUpdateControl2)
+	ctrl.sendData([]byte{displayUpdateEnableClock | displayUpdateEnableAnalog})
 
+	ctrl.sendCommand(masterActivation)
 	ctrl.waitUntilIdle()
 }
 
diff --git a/waveshare2in13v2/controller_test.go b/waveshare2in13v2/controller_test.go
index 5c6436f..16496ae 100644
--- a/waveshare2in13v2/controller_test.go
+++ b/waveshare2in13v2/controller_test.go
@@ -92,6 +92,8 @@ func TestConfigDisplayMode(t *testing.T) {
 				{cmd: borderWaveformControl, data: []byte{0x03}},
 				{cmd: writeLutRegister, data: bytes.Repeat([]byte{'F'}, 70)},
 				{cmd: 0x37, data: []byte{0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00}},
+				{cmd: displayUpdateControl2, data: []byte{0xc0}},
+				{cmd: masterActivation},
 			},
 		},
 		{