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Kernel: Flush data cache before passing a buffer to the VC Mailbox

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Otherwise, the message's contents might be in the cache only, so
VideoCore will read stale/garbage data from main memory.

This fixes framebuffer setup on bare metal with the data cache enabled.
This commit is contained in:
Daniel Bertalan 2023-05-16 15:27:50 +02:00 • committed by Andrew Kaster
parent 0cbcdb227f
commit 3d383974cd
2 changed files with 24 additions and 0 deletions
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5
Kernel/Arch/aarch64/RPi/Mailbox.cpp
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@ -4,6 +4,7 @@
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Arch/aarch64/ASM_wrapper.h>
#include <Kernel/Arch/aarch64/RPi/MMIO.h>
#include <Kernel/Arch/aarch64/RPi/Mailbox.h>
@ -90,6 +91,10 @@ bool Mailbox::send_queue(void* queue, u32 queue_size) const
// The mailbox message is 32-bit based, so this assumes that message is in the first 4 GiB.
u32 request = static_cast<u32>(reinterpret_cast<FlatPtr>(queue) & ~0xF) | (channel & 0xF);
// The queue buffer might point to normal cached memory, so flush any writes that are in cache and not visible to VideoCore.
Aarch64::Asm::flush_data_cache((FlatPtr)queue, queue_size);
mmio.write(MBOX_WRITE_DATA, request);
for (;;) {