From b9fa0c8b6d570ed8ef904da1c947786fb684ab5e Mon Sep 17 00:00:00 2001
From: Dan Halbert <halbert@halwitz.org>
Date: Thu, 24 Oct 2024 23:58:14 -0400
Subject: [PATCH] Use volatile pointerwhen invalidating PSRAM cache

---
 ports/raspberrypi/supervisor/internal_flash.c | 4 +++-
 ports/raspberrypi/supervisor/port.c           | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/ports/raspberrypi/supervisor/internal_flash.c b/ports/raspberrypi/supervisor/internal_flash.c
index b667112b5880..1b328cbc5a7b 100644
--- a/ports/raspberrypi/supervisor/internal_flash.c
+++ b/ports/raspberrypi/supervisor/internal_flash.c
@@ -49,11 +49,13 @@ static uint32_t m1_timing;
 static void save_psram_settings(void) {
     #ifdef PICO_RP2350
     // We're about to invalidate the XIP cache, clean it first to commit any dirty writes to PSRAM
-    uint8_t *maintenance_ptr = (uint8_t *)XIP_MAINTENANCE_BASE;
+    volatile uint8_t *maintenance_ptr = (uint8_t *)XIP_MAINTENANCE_BASE;
     for (int i = 1; i < 16 * 1024; i += 8) {
         // Background info: https://forums.raspberrypi.com/viewtopic.php?t=378249
         maintenance_ptr[i] = 0; // Clean
+        __compiler_memory_barrier();
         maintenance_ptr[i - 1] = 0; // Explicitly invalidate
+        __compiler_memory_barrier();
     }
 
     m1_timing = qmi_hw->m[1].timing;
diff --git a/ports/raspberrypi/supervisor/port.c b/ports/raspberrypi/supervisor/port.c
index ffa25d12404e..13e5abb61216 100644
--- a/ports/raspberrypi/supervisor/port.c
+++ b/ports/raspberrypi/supervisor/port.c
@@ -244,7 +244,7 @@ void port_heap_init(void) {
     _heap = tlsf_create_with_pool(heap_bottom, size, 64 * 1024 * 1024);
     _ram_pool = tlsf_get_pool(_heap);
     if (_psram_size > 0) {
-        _psram_pool = tlsf_add_pool(_heap, (void *)0x11000004, _psram_size - 4);
+        _psram_pool = tlsf_add_pool(_heap, (void *)0x11000000, _psram_size);
     }
 }