From 44dcd82d78bf4da00ac00f1738d9b95e9735df9e Mon Sep 17 00:00:00 2001
From: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
Date: Fri, 21 Aug 2026 07:58:11 +1200
Subject: [PATCH] [mipi_spi] Toggle D/C only while holding the SPI bus (#18529)

---
 esphome/components/mipi_spi/mipi_spi.h | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/esphome/components/mipi_spi/mipi_spi.h b/esphome/components/mipi_spi/mipi_spi.h
index b269f46dc9..2552451bd7 100644
--- a/esphome/components/mipi_spi/mipi_spi.h
+++ b/esphome/components/mipi_spi/mipi_spi.h
@@ -246,33 +246,36 @@ class MipiSpi : public display::Display,
       this->write_cmd_addr_data(8, 0x02, 24, cmd << 8, bytes, len);
       this->disable();
     } else if constexpr (BUS_TYPE == BUS_TYPE_OCTAL) {
-      this->dc_pin_->digital_write(false);
+      // Toggle D/C only while holding the bus; on boards where D/C doubles as
+      // another bus signal, driving it while another device owns the bus
+      // corrupts that device's transfer.
       this->enable();
+      this->dc_pin_->digital_write(false);
       this->write_cmd_addr_data(0, 0, 0, 0, &cmd, 1, 8);
-      this->disable();
       this->dc_pin_->digital_write(true);
+      this->disable();
       if (len != 0) {
         this->enable();
         this->write_cmd_addr_data(0, 0, 0, 0, bytes, len, 8);
         this->disable();
       }
     } else if constexpr (BUS_TYPE == BUS_TYPE_SINGLE) {
-      this->dc_pin_->digital_write(false);
       this->enable();
+      this->dc_pin_->digital_write(false);
       this->write_byte(cmd);
-      this->disable();
       this->dc_pin_->digital_write(true);
+      this->disable();
       if (len != 0) {
         this->enable();
         this->write_array(bytes, len);
         this->disable();
       }
     } else if constexpr (BUS_TYPE == BUS_TYPE_SINGLE_16) {
-      this->dc_pin_->digital_write(false);
       this->enable();
+      this->dc_pin_->digital_write(false);
       this->write_byte(cmd);
-      this->disable();
       this->dc_pin_->digital_write(true);
+      this->disable();
       for (size_t i = 0; i != len; i++) {
         this->enable();
         this->write_byte(0);