From c8231f97b0f0cc3bf6d7c71d946db59c87edfa28 Mon Sep 17 00:00:00 2001
From: Matteo Golin <matteo.golin@gmail.com>
Date: Mon, 13 Jul 2026 17:27:54 -0400
Subject: [PATCH] bcm2711/mailbox: Invalidate cache before read

Cache must be invalidated before the buffer is read since the
VideoCore's write will not invalidate the cache.

Signed-off-by: Matteo Golin <matteo.golin@gmail.com>
---
 arch/arm64/src/bcm2711/bcm2711_mailbox.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/src/bcm2711/bcm2711_mailbox.c b/arch/arm64/src/bcm2711/bcm2711_mailbox.c
index 27d277a7daf..eb8d66d455e 100644
--- a/arch/arm64/src/bcm2711/bcm2711_mailbox.c
+++ b/arch/arm64/src/bcm2711/bcm2711_mailbox.c
@@ -282,6 +282,8 @@ static int bcm2711_mbox_sendreq(FAR uint32_t *buf, uint8_t n)
    * docs).
    */
 
+  up_invalidate_dcache(bufptr, bufptr + n); /* So we read fresh data */
+
   if (retbuf != bufptr)
     {
       ipcerr("Expected %08x, got %08x", bufptr, res);