From bb3784204153192b163e90eea1aa337044080760 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Tue, 13 Oct 2026 17:40:19 -1000
Subject: [PATCH] [epaper_spi] Keep the state name table in flash

---
 esphome/components/epaper_spi/epaper_spi.cpp | 27 +++++++++-----------
 esphome/components/epaper_spi/epaper_spi.h   |  2 +-
 2 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/esphome/components/epaper_spi/epaper_spi.cpp b/esphome/components/epaper_spi/epaper_spi.cpp
index 7b962d59ea8..1c55f1cd391 100644
--- a/esphome/components/epaper_spi/epaper_spi.cpp
+++ b/esphome/components/epaper_spi/epaper_spi.cpp
@@ -3,21 +3,18 @@
 #include "esphome/core/application.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
+#include "esphome/core/progmem.h"
 
 namespace esphome::epaper_spi {
 
 ESPHOME_LOG_TAG(TAG, "epaper_spi");
 static constexpr size_t EPAPER_MAX_CMD_LOG_BYTES = 128;
 
-static constexpr const char *const EPAPER_STATE_STRINGS[] = {
-    "IDLE",          "UPDATE",   "RESET",          "RESET_END", "SHOULD_WAIT", "INITIALISE",
-    "TRANSFER_DATA", "POWER_ON", "REFRESH_SCREEN", "POWER_OFF", "DEEP_SLEEP",
-};
+PROGMEM_STRING_TABLE(EPaperStateStrings, "IDLE", "UPDATE", "RESET", "RESET_END", "SHOULD_WAIT", "INITIALISE",
+                     "TRANSFER_DATA", "POWER_ON", "REFRESH_SCREEN", "POWER_OFF", "DEEP_SLEEP", "Unknown");
 
-const char *EPaperBase::epaper_state_to_string_() {
-  if (auto idx = static_cast<unsigned>(this->state_); idx < std::size(EPAPER_STATE_STRINGS))
-    return EPAPER_STATE_STRINGS[idx];
-  return "Unknown";
+const LogString *EPaperBase::epaper_state_to_string_() {
+  return EPaperStateStrings::get_log_str(static_cast<uint8_t>(this->state_), EPaperStateStrings::LAST_INDEX);
 }
 
 void EPaperBase::setup() {
@@ -120,7 +117,7 @@ void EPaperBase::update_effective_transform_() {
 
 void EPaperBase::update() {
   if (this->state_ != EPaperState::IDLE) {
-    ESP_LOGE(TAG, "Display already in state %s", epaper_state_to_string_());
+    ESP_LOGE(TAG, "Display already in state %s", LOG_STR_ARG(epaper_state_to_string_()));
     return;
   }
   this->set_state_(EPaperState::UPDATE);
@@ -160,7 +157,7 @@ void EPaperBase::loop() {
       }
 #if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
       if (now - this->waiting_for_idle_last_print_ >= 1000) {
-        ESP_LOGV(TAG, "Waiting for idle in state %s", this->epaper_state_to_string_());
+        ESP_LOGV(TAG, "Waiting for idle in state %s", LOG_STR_ARG(this->epaper_state_to_string_()));
         this->waiting_for_idle_last_print_ = millis();
       }
 #endif
@@ -173,7 +170,7 @@ void EPaperBase::loop() {
 // The busy pin never cleared: give up on this update so later ones are not refused, and make the next one full
 void EPaperBase::abandon_update_() {
   ESP_LOGE(TAG, "Display stayed busy for %u s in state %s; check the busy pin", (unsigned) this->busy_timeout_seconds_,
-           this->epaper_state_to_string_());
+           LOG_STR_ARG(this->epaper_state_to_string_()));
   this->status_set_warning(LOG_STR("Busy pin timeout"));
   if (this->state_ == EPaperState::TRANSFER_DATA)
     this->abort_transfer();
@@ -193,10 +190,10 @@ void EPaperBase::abandon_update_() {
  * Should a subclassed class need to override this, the method will need to be made virtual.
  */
 void EPaperBase::process_state_() {
-  ESP_LOGV(TAG, "Process state entered in state %s", epaper_state_to_string_());
+  ESP_LOGV(TAG, "Process state entered in state %s", LOG_STR_ARG(epaper_state_to_string_()));
   switch (this->state_) {
     default:
-      ESP_LOGE(TAG, "Display is in unhandled state %s", epaper_state_to_string_());
+      ESP_LOGE(TAG, "Display is in unhandled state %s", LOG_STR_ARG(epaper_state_to_string_()));
       this->set_state_(EPaperState::IDLE);
       break;
     case EPaperState::IDLE:
@@ -266,7 +263,7 @@ void EPaperBase::process_state_() {
 }
 
 void EPaperBase::set_state_(EPaperState state, uint16_t delay) {
-  ESP_LOGV(TAG, "Exit state %s", this->epaper_state_to_string_());
+  ESP_LOGV(TAG, "Exit state %s", LOG_STR_ARG(this->epaper_state_to_string_()));
   this->state_ = state;
   this->wait_for_idle_(state > EPaperState::SHOULD_WAIT);
   // allow subclasses to nominate delays
@@ -274,7 +271,7 @@ void EPaperBase::set_state_(EPaperState state, uint16_t delay) {
     delay = this->next_delay_;
   this->next_delay_ = 0;
   this->delay_until_ = millis() + delay;
-  ESP_LOGV(TAG, "Enter state %s, delay %u, wait_for_idle=%s", this->epaper_state_to_string_(), delay,
+  ESP_LOGV(TAG, "Enter state %s, delay %u, wait_for_idle=%s", LOG_STR_ARG(this->epaper_state_to_string_()), delay,
            TRUEFALSE(this->waiting_for_idle_));
   if (state == EPaperState::IDLE) {
     this->disable_loop();
diff --git a/esphome/components/epaper_spi/epaper_spi.h b/esphome/components/epaper_spi/epaper_spi.h
index 384b9cb0181..415d518acf4 100644
--- a/esphome/components/epaper_spi/epaper_spi.h
+++ b/esphome/components/epaper_spi/epaper_spi.h
@@ -121,7 +121,7 @@ class EPaperBase : public Display,
   bool is_using_partial_update_() const { return this->full_update_every_ > 1; }
   void process_state_();
 
-  const char *epaper_state_to_string_();
+  const LogString *epaper_state_to_string_();
   bool is_idle_() const;
   void setup_pins_() const;
   virtual bool reset();