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Commit 2d3b7d6e authored by Andrew Jackson's avatar Andrew Jackson Committed by Greg Kroah-Hartman
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serial: pl011: Don't enable RX DMA if residue processing not supported 



If the DMA engine doesn't support residue processing then the RX DMA
handling won't work terribly well if polling is enabled.  So, disable
RX DMA if residue handling isn't available.

Signed-off-by: default avatarAndrew Jackson <Andrew.Jackson@arm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c64be923

drivers/tty/serial/amba-pl011.c

+15 −0
Original line number Diff line number Diff line
@@ -322,7 +322,22 @@ static void pl011_dma_probe_initcall(struct device *dev, struct uart_amba_port * 
			.src_maxburst = uap->fifosize >> 2,

			.device_fc = false,

		};

		struct dma_slave_caps caps;



		/*

		 * Some DMA controllers provide information on their capabilities.

		 * If the controller does, check for suitable residue processing

		 * otherwise assime all is well.

		 */

		if (0 == dma_get_slave_caps(chan, &caps)) {

			if (caps.residue_granularity ==

					DMA_RESIDUE_GRANULARITY_DESCRIPTOR) {

				dma_release_channel(chan);

				dev_info(uap->port.dev,

					"RX DMA disabled - no residue processing\n");

				return;

			}

		}

		dmaengine_slave_config(chan, &rx_conf);

		uap->dmarx.chan = chan;