Hi Andy, I saw that you have discovered that commit ec5a11a91eec ("serial: 8250: Validate dmaengine rx chan meets requirements") introduced a regression in the 8250 uart driver. For SoCFPGA platform, I am seeing this error: [ 5.541751] ttyS0 - failed to request DMA Reverting the commit ec5a11a91eec removes the error. I saw that you started the discussion, but I didn't see that a patch was included[1]. The following patch seems to fix the error, but I'm not sure if it's the same fix that you had in mind. Thanks, Dinh [1] http://marc.info/?l=linux-serial&m=146254187602862&w=2 ---------------8<------------ diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c index 7f33d1c..847a203 100644 --- a/drivers/tty/serial/8250/8250_dma.c +++ b/drivers/tty/serial/8250/8250_dma.c @@ -176,7 +176,7 @@ int serial8250_request_dma(struct uart_8250_port *p) ret = dma_get_slave_caps(dma->rxchan, &caps); if (ret) goto release_rx; - if (!caps.cmd_pause || !caps.cmd_terminate || + if ((!caps.cmd_pause || !caps.cmd_terminate) && caps.residue_granularity == DMA_RESIDUE_GRANULARITY_DESCRIPTOR) { ret = -EINVAL; goto release_rx; -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html