* [PATCH 4/5] serial: pl011: Don't enable RX DMA if residue processing not supported
@ 2014-11-07 14:14 ` Andrew Jackson
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Jackson @ 2014-11-07 14:14 UTC (permalink / raw)
To: Russell King - ARM Linux, Greg Kroah-Hartman, Jiri Slaby,
linux-serial, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
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 <Andrew.Jackson@arm.com>
---
drivers/tty/serial/amba-pl011.c | 17 ++++++++++++++++-
1 files changed, 16 insertions(+), 1 deletions(-)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 7c5e263..79b9c93 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -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;
--
1.7.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* [PATCH 4/5] serial: pl011: Don't enable RX DMA if residue processing not supported
@ 2014-11-07 14:14 ` Andrew Jackson
0 siblings, 0 replies; 2+ messages in thread
From: Andrew Jackson @ 2014-11-07 14:14 UTC (permalink / raw)
To: linux-arm-kernel
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 <Andrew.Jackson@arm.com>
---
drivers/tty/serial/amba-pl011.c | 17 ++++++++++++++++-
1 files changed, 16 insertions(+), 1 deletions(-)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 7c5e263..79b9c93 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -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;
--
1.7.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2014-11-07 14:15 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2014-11-07 14:14 [PATCH 4/5] serial: pl011: Don't enable RX DMA if residue processing not supported Andrew Jackson
2014-11-07 14:14 ` Andrew Jackson
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.