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Subject[PATCH v2][bfin-sport-uart] Walk around RX underflow hardware issue in 32-bit SPORT RX reading
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If another interrupt fires while doing a 32-bit read from RX FIFO,
a fake RX underflow error will be generated. So disable interrupts
to prevent interruption while reading the FIFO.


Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
---
drivers/serial/bfin_sport_uart.h | 16 +++++++++++++++-
1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/drivers/serial/bfin_sport_uart.h b/drivers/serial/bfin_sport_uart.h
index 671d41c..f4e5a83 100644
--- a/drivers/serial/bfin_sport_uart.h
+++ b/drivers/serial/bfin_sport_uart.h
@@ -43,7 +43,21 @@
#define SPORT_GET_TFSDIV(sport) bfin_read16(((sport)->port.membase + OFFSET_TFSDIV))
#define SPORT_GET_TX(sport) bfin_read16(((sport)->port.membase + OFFSET_TX))
#define SPORT_GET_RX(sport) bfin_read16(((sport)->port.membase + OFFSET_RX))
-#define SPORT_GET_RX32(sport) bfin_read32(((sport)->port.membase + OFFSET_RX))
+/*
+ * If another interrupt fires while doing a 32-bit read from RX FIFO,
+ * a fake RX underflow error will be generated. So disable interrupts
+ * to prevent interruption while reading the FIFO.
+ * Once hardware design can root cause and officially log this, we can
+ * update the code to use a standard ANOMALY_XXX define.
+ */
+#define SPORT_GET_RX32(sport) \
+({ \
+ unsigned int __ret; \
+ local_irq_disable(); \
+ __ret = bfin_read32(((sport)->port.membase + OFFSET_RX)); \
+ local_irq_enable(); \
+ __ret; \
+})
#define SPORT_GET_RCR1(sport) bfin_read16(((sport)->port.membase + OFFSET_RCR1))
#define SPORT_GET_RCR2(sport) bfin_read16(((sport)->port.membase + OFFSET_RCR2))
#define SPORT_GET_RCLKDIV(sport) bfin_read16(((sport)->port.membase + OFFSET_RCLKDIV))
--
1.6.0




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