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fix: prevent Serial.printf from blocking when USB disconnected
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On ESP32-C3 with USB CDC, Serial.printf() blocks indefinitely when USB
is not connected. This caused device freezes when booted without USB.

Solution: Call Serial.setTxTimeoutMs(0) after Serial.begin() to make
all Serial output non-blocking.

Also added if (Serial) guards to high-traffic logging paths in
EpubReaderActivity as belt-and-suspenders protection.

Includes documentation of the debugging process and Serial call inventory.

Also applies clang-format to fix pre-existing formatting issues.
This commit is contained in:
cottongin
2026-01-28 15:57:31 -05:00
parent f3075002c1
commit 4db384edb6
59 changed files with 989 additions and 621 deletions
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46
src/activities/boot_sleep/SleepActivity.cpp
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@@ -184,7 +184,8 @@ void SleepActivity::renderBitmapSleepScreen(const Bitmap& bitmap, const std::str
drawHeight = 0;
fillWidth = static_cast<int>(bitmap.getWidth());
fillHeight = static_cast<int>(bitmap.getHeight());
Serial.printf("[%lu] [SLP] ACTUAL mode: centering at %d, %d (fill: %dx%d)\n", millis(), x, y, fillWidth, fillHeight);
Serial.printf("[%lu] [SLP] ACTUAL mode: centering at %d, %d (fill: %dx%d)\n", millis(), x, y, fillWidth,
fillHeight);
} else if (coverMode == CrossPointSettings::SLEEP_SCREEN_COVER_MODE::CROP) {
// CROP mode: Scale to fill screen completely (may crop edges)
// Calculate crop values to fill the screen while maintaining aspect ratio
@@ -221,8 +222,8 @@ void SleepActivity::renderBitmapSleepScreen(const Bitmap& bitmap, const std::str
// Center the scaled image
x = (pageWidth - fillWidth) / 2;
y = (pageHeight - fillHeight) / 2;
Serial.printf("[%lu] [SLP] FIT mode: scale %f, scaled size %d x %d, position %d, %d\n", millis(), scale,
fillWidth, fillHeight, x, y);
Serial.printf("[%lu] [SLP] FIT mode: scale %f, scaled size %d x %d, position %d, %d\n", millis(), scale, fillWidth,
fillHeight, x, y);
}
// Get edge luminance values (from cache or calculate)
@@ -232,9 +233,8 @@ void SleepActivity::renderBitmapSleepScreen(const Bitmap& bitmap, const std::str
const uint8_t leftGray = quantizeGray(edges.left);
const uint8_t rightGray = quantizeGray(edges.right);
Serial.printf("[%lu] [SLP] Edge luminance: T=%d B=%d L=%d R=%d -> gray levels T=%d B=%d L=%d R=%d\n",
millis(), edges.top, edges.bottom, edges.left, edges.right,
topGray, bottomGray, leftGray, rightGray);
Serial.printf("[%lu] [SLP] Edge luminance: T=%d B=%d L=%d R=%d -> gray levels T=%d B=%d L=%d R=%d\n", millis(),
edges.top, edges.bottom, edges.left, edges.right, topGray, bottomGray, leftGray, rightGray);
// Check if greyscale pass should be used (PR #476: skip if filter is applied)
const bool hasGreyscale = bitmap.hasGreyscale() &&
@@ -418,10 +418,10 @@ std::string SleepActivity::getEdgeCachePath(const std::string& bmpPath) {
uint8_t SleepActivity::quantizeGray(uint8_t lum) {
// Quantize luminance (0-255) to 4-level grayscale (0-3)
// Thresholds tuned for X4 display gray levels
if (lum < 43) return 0; // black
if (lum < 128) return 1; // dark gray
if (lum < 213) return 2; // light gray
return 3; // white
if (lum < 43) return 0; // black
if (lum < 128) return 1; // dark gray
if (lum < 213) return 2; // light gray
return 3; // white
}
EdgeLuminance SleepActivity::getEdgeLuminance(const Bitmap& bitmap, const std::string& bmpPath) const {
@@ -434,8 +434,7 @@ EdgeLuminance SleepActivity::getEdgeLuminance(const Bitmap& bitmap, const std::s
uint8_t cacheData[EDGE_CACHE_SIZE];
if (cacheFile.read(cacheData, EDGE_CACHE_SIZE) == EDGE_CACHE_SIZE) {
// Extract cached file size
const uint32_t cachedSize = static_cast<uint32_t>(cacheData[0]) |
(static_cast<uint32_t>(cacheData[1]) << 8) |
const uint32_t cachedSize = static_cast<uint32_t>(cacheData[0]) | (static_cast<uint32_t>(cacheData[1]) << 8) |
(static_cast<uint32_t>(cacheData[2]) << 16) |
(static_cast<uint32_t>(cacheData[3]) << 24);
@@ -448,8 +447,8 @@ EdgeLuminance SleepActivity::getEdgeLuminance(const Bitmap& bitmap, const std::s
result.bottom = cacheData[5];
result.left = cacheData[6];
result.right = cacheData[7];
Serial.printf("[%lu] [SLP] Edge cache hit for %s: T=%d B=%d L=%d R=%d\n", millis(), bmpPath.c_str(),
result.top, result.bottom, result.left, result.right);
Serial.printf("[%lu] [SLP] Edge cache hit for %s: T=%d B=%d L=%d R=%d\n", millis(), bmpPath.c_str(), result.top,
result.bottom, result.left, result.right);
cacheFile.close();
return result;
}
@@ -462,8 +461,8 @@ EdgeLuminance SleepActivity::getEdgeLuminance(const Bitmap& bitmap, const std::s
// Cache miss - calculate edge luminance
Serial.printf("[%lu] [SLP] Calculating edge luminance for %s\n", millis(), bmpPath.c_str());
result = bitmap.detectEdgeLuminance(2); // Sample 2 pixels deep for stability
Serial.printf("[%lu] [SLP] Edge luminance detected: T=%d B=%d L=%d R=%d\n", millis(),
result.top, result.bottom, result.left, result.right);
Serial.printf("[%lu] [SLP] Edge luminance detected: T=%d B=%d L=%d R=%d\n", millis(), result.top, result.bottom,
result.left, result.right);
// Get BMP file size from already-opened bitmap for cache
const uint32_t fileSize = bitmap.getFileSize();
@@ -534,8 +533,7 @@ bool SleepActivity::tryRenderCachedCoverSleep(const std::string& bookPath, bool
cacheFile.close();
// Extract cached values
const uint32_t cachedBmpSize = static_cast<uint32_t>(cacheData[0]) |
(static_cast<uint32_t>(cacheData[1]) << 8) |
const uint32_t cachedBmpSize = static_cast<uint32_t>(cacheData[0]) | (static_cast<uint32_t>(cacheData[1]) << 8) |
(static_cast<uint32_t>(cacheData[2]) << 16) |
(static_cast<uint32_t>(cacheData[3]) << 24);
EdgeLuminance cachedEdges;
@@ -548,8 +546,8 @@ bool SleepActivity::tryRenderCachedCoverSleep(const std::string& bookPath, bool
// Check if cover mode matches (for EPUB)
const uint8_t currentCoverMode = cropped ? 1 : 0;
if (StringUtils::checkFileExtension(bookPath, ".epub") && cachedCoverMode != currentCoverMode) {
Serial.printf("[SLP] Cover mode changed (cached=%d, current=%d), invalidating cache\n",
cachedCoverMode, currentCoverMode);
Serial.printf("[SLP] Cover mode changed (cached=%d, current=%d), invalidating cache\n", cachedCoverMode,
currentCoverMode);
return false;
}
@@ -571,8 +569,8 @@ bool SleepActivity::tryRenderCachedCoverSleep(const std::string& bookPath, bool
// Check if BMP file size matches cache
const uint32_t currentBmpSize = bmpFile.size();
if (currentBmpSize != cachedBmpSize || currentBmpSize == 0) {
Serial.printf("[SLP] BMP size mismatch (cached=%lu, current=%lu)\n",
static_cast<unsigned long>(cachedBmpSize), static_cast<unsigned long>(currentBmpSize));
Serial.printf("[SLP] BMP size mismatch (cached=%lu, current=%lu)\n", static_cast<unsigned long>(cachedBmpSize),
static_cast<unsigned long>(currentBmpSize));
bmpFile.close();
return false;
}
@@ -585,8 +583,8 @@ bool SleepActivity::tryRenderCachedCoverSleep(const std::string& bookPath, bool
return false;
}
Serial.printf("[%lu] [SLP] Using cached cover sleep: %s (T=%d B=%d L=%d R=%d)\n", millis(),
coverBmpPath.c_str(), cachedEdges.top, cachedEdges.bottom, cachedEdges.left, cachedEdges.right);
Serial.printf("[%lu] [SLP] Using cached cover sleep: %s (T=%d B=%d L=%d R=%d)\n", millis(), coverBmpPath.c_str(),
cachedEdges.top, cachedEdges.bottom, cachedEdges.left, cachedEdges.right);
// Render the bitmap with cached edge values
// We call renderBitmapSleepScreen which will use getEdgeLuminance internally,