When this target got updated to 4.14, this patch got removed to re-evaluate if it was still needed.
Extensive testing now shows this issue is still present. Let's re-add the patch to fix it for now. As the uart bus is very low bandwidth .. performance impact is negligible. Boot log: [ 22.513051] imx-uart 2020000.serial: DMA transaction error. [ 22.522721] imx-uart 2020000.serial: DMA transaction error. As a sidenote: The patch mentiones an issue with RS485, but the bootlog errors above were recorded with the uart ports in standard RS232 mode. Compile/Run-tested on imx6/GW5200 Signed-off-by: Koen Vandeputte <koen.vandepu...@ncentric.com> --- .../imx6/patches-4.14/210-disable-uart-dma.patch | 23 ++++++++++++++++++++++ 1 file changed, 23 insertions(+) create mode 100644 target/linux/imx6/patches-4.14/210-disable-uart-dma.patch diff --git a/target/linux/imx6/patches-4.14/210-disable-uart-dma.patch b/target/linux/imx6/patches-4.14/210-disable-uart-dma.patch new file mode 100644 index 000000000000..6abbb9330188 --- /dev/null +++ b/target/linux/imx6/patches-4.14/210-disable-uart-dma.patch @@ -0,0 +1,23 @@ +Based on following upstream patch by Tim Harvey (Gateworks): + +https://github.com/Gateworks/openwrt/commit/80a01b6582f94c4547f39d3a25e0a1e9b6eb9877 + +TX complete DMA messages are getting missed. +This is also currently an issue in mainline. +For now we will disable DMA in serial/imx.c. + +This resolves an issue encountered with RS485 transmit. + +--- a/drivers/tty/serial/imx.c ++++ b/drivers/tty/serial/imx.c +@@ -1268,10 +1268,6 @@ static int imx_startup(struct uart_port + + writel(temp & ~UCR4_DREN, sport->port.membase + UCR4); + +- /* Can we enable the DMA support? */ +- if (!uart_console(port) && !sport->dma_is_inited) +- imx_uart_dma_init(sport); +- + spin_lock_irqsave(&sport->port.lock, flags); + /* Reset fifo's and state machines */ + i = 100; -- 2.7.4 _______________________________________________ Lede-dev mailing list Ledeemail@example.com http://lists.infradead.org/mailman/listinfo/lede-dev