serial: pl011: Don't enable RX DMA if residue processing not supported
PATCH 4/5 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 Andrew Jackson <[email protected]>
--- drivers/tty/serial/amba-pl011.c | 17 ++++++++++++++++- 1 files changed, 16 insertions(+), 1 deletions(-)
drivers/tty/serial/amba-pl011.c +15 -0
@@ -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;
Signature · 1 line
1.7.1