Disable DMA for Pi 5's UART0#6742
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pelwell merged 2 commits intoraspberrypi:rpi-6.12.yfrom Mar 26, 2025
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This reverts commit 898d640. Signed-off-by: Phil Elwell <phil@raspberrypi.com>
DMA has been enabled on RP1's UART0, but with mixed success. Transmits seem to work, but the DMA interface is not well suited to receiving arbitrary amounts of data. In particular, the PL011 driver is slow to pass on the received data, batching it into large blocks. On balance, it's better to just disable the DMA support. As with the other UARTs, the required runes are left in the DTS as comments. Signed-off-by: Phil Elwell <phil@raspberrypi.com>
popcornmix
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…cmdline See: raspberrypi/linux#6740 kernel: Disable DMA for Pi 5's UART0 See: raspberrypi/linux#6742
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…cmdline See: raspberrypi/linux#6740 kernel: Disable DMA for Pi 5's UART0 See: raspberrypi/linux#6742
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Previous Pis have managed without using DMA with the UARTs, and it has been seen to cause problems on the receive side, so play safe and disable it.