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ramips: reduce ARCH_DMA_MINALIGN

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Currently, Ralink SoCs use the default ARCH_DMA_MINALIGN value of 128
bytes defined in mach-generic. This is excessive for these platforms
and leads to significant memory waste in kmalloc.

Override ARCH_DMA_MINALIGN to use L1_CACHE_BYTES, which is 16 bytes for
RT288X and 32 bytes for other Ralink SoCs.

Signed-off-by: Qingfang Deng <dqfext@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/23314
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
This commit is contained in:
Qingfang Deng 2026-05-27 09:29:06 +08:00 committed by Hauke Mehrtens
parent 028dc3f57a
commit 0bc1d99bcf
1 changed files with 31 additions and 0 deletions
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31
target/linux/ramips/patches-6.18/110-MIPS-ralink-reduce-ARCH_DMA_MINALIGN.patch Normal file
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@ -0,0 +1,31 @@
From 1dc85756b759c3ecd21a22b0aef84ed41ddc7596 Mon Sep 17 00:00:00 2001
From: Qingfang Deng <qingfang.deng@linux.dev>
Date: Tue, 28 Apr 2026 16:25:40 +0800
Subject: [PATCH] MIPS: ralink: reduce ARCH_DMA_MINALIGN
Currently, Ralink SoCs use the default ARCH_DMA_MINALIGN value of 128
bytes defined in mach-generic. This is excessive for these platforms
and leads to significant memory waste in kmalloc.
Override ARCH_DMA_MINALIGN to use L1_CACHE_BYTES, which is 16 bytes for
RT288X and 32 bytes for other Ralink SoCs.
Signed-off-by: Qingfang Deng <qingfang.deng@linux.dev>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
---
arch/mips/include/asm/mach-ralink/kmalloc.h | 9 +++++++++
1 file changed, 9 insertions(+)
create mode 100644 arch/mips/include/asm/mach-ralink/kmalloc.h
--- /dev/null
+++ b/arch/mips/include/asm/mach-ralink/kmalloc.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_MACH_RALINK_KMALLOC_H
+#define __ASM_MACH_RALINK_KMALLOC_H
+
+#ifdef CONFIG_DMA_NONCOHERENT
+#define ARCH_DMA_MINALIGN L1_CACHE_BYTES
+#endif
+
+#endif /* __ASM_MACH_RALINK_KMALLOC_H */