On MT7621 it was observed, that enabling highmem support causes a significant
performance drop, as documented in: https://github.com/openwrt/openwrt/issues/13151
By adjusting the highmem start offset, we avoid leaving any RAM unaddressable,
even on devices with 512 MB
Fixes: https://github.com/openwrt/openwrt/issues/13151
Signed-off-by: Felix Fietkau <nbd@nbd.name>
CONFIG_AT803X_PHY=y
CONFIG_BLK_MQ_PCI=y
CONFIG_BOARD_SCACHE=y
-CONFIG_BOUNCE=y
CONFIG_CEVT_R4K=y
CONFIG_CLKSRC_MIPS_GIC=y
CONFIG_CLK_MT7621=y
CONFIG_HAS_DMA=y
CONFIG_HAS_IOMEM=y
CONFIG_HAS_IOPORT_MAP=y
-CONFIG_HIGHMEM=y
CONFIG_I2C=y
CONFIG_I2C_ALGOBIT=y
CONFIG_I2C_BOARDINFO=y
CONFIG_IRQ_FORCED_THREADING=y
CONFIG_IRQ_MIPS_CPU=y
CONFIG_IRQ_WORK=y
-CONFIG_KMAP_LOCAL=y
CONFIG_LED_TRIGGER_PHY=y
CONFIG_LIBFDT=y
CONFIG_LOCK_DEBUGGING_SUPPORT=y
--- /dev/null
+From: Felix Fietkau <nbd@nbd.name>
+Date: Mon Jul 24 13:29:13 CEST 2023
+Subject: [PATCH] mips: ralink: increase highmem start
+
+Increase highmem start address in order to support devices with 512 MB memory
+and MT7621 SoC
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+--- a/arch/mips/include/asm/mach-ralink/spaces.h
++++ b/arch/mips/include/asm/mach-ralink/spaces.h
+@@ -5,6 +5,7 @@
+ #define PCI_IOBASE _AC(0xa0000000, UL)
+ #define PCI_IOSIZE SZ_16M
+ #define IO_SPACE_LIMIT (PCI_IOSIZE - 1)
++#define HIGHMEM_START _AC(0x24000000, UL)
+
+ #include <asm/mach-generic/spaces.h>
+ #endif