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alif/vfs_rom_ioctl: Disable interrupts while programming MRAM. - #19732
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An interrupt taken while an MRAM line is being programmed can wedge the MRAM controller. The core hangs, and nothing short of a power cycle recovers the chip, since the secure enclave boots from MRAM too. The Alif MRAM driver requires interrupts to be disabled around MRAM writes, followed by a DSB and a D-cache clean. Program MRAM in 256 byte blocks, each with interrupts disabled, then a DSB and a D-cache clean of the block before interrupts are re-enabled. Each interrupts-off window stays well under 1ms. Signed-off-by: Kwabena W. Agyeman <kwagyeman@live.com>
dpgeorge
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Oct 5, 2026
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Looks good. The reasoning matches the comments for Alif_CMSIS/Source/Driver_MRAM.c:MRAM_write().
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An interrupt taken while an MRAM line is being programmed can wedge the
MRAM controller. The core hangs, and nothing short of a power cycle
recovers the chip, since the secure enclave boots from MRAM too. The
Alif MRAM driver requires interrupts to be disabled around MRAM writes,
followed by a DSB and a D-cache clean.
Program MRAM in 256 byte blocks, each with interrupts disabled, then a
DSB and a D-cache clean of the block before interrupts are re-enabled.
Each interrupts-off window stays well under 1ms.
Issue found while trying to update coprocessor ROMFS MRAM from HP core.