lantiq: fix a race condition in the SPI driver leading to rx FIFO overflows (and...

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
SVN-Revision: 47770

diff --git a/target/linux/lantiq/patches-4.1/0033-SPI-MIPS-lantiq-adds-spi-xway.patch b/target/linux/lantiq/patches-4.1/0033-SPI-MIPS-lantiq-adds-spi-xway.patch
index 956dd1036809376a65eb99ff327e0b50c73001b6..93a2972599eb03318ad00d1d315bbabe74a833ed 100644 (file)
--- a/target/linux/lantiq/patches-4.1/0033-SPI-MIPS-lantiq-adds-spi-xway.patch
+++ b/target/linux/lantiq/patches-4.1/0033-SPI-MIPS-lantiq-adds-spi-xway.patch
@@ -42,7 +42,7 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
 +obj-$(CONFIG_SPI_XWAY)                        += spi-xway.o
 --- /dev/null
 +++ b/drivers/spi/spi-xway.c
-@@ -0,0 +1,991 @@
+@@ -0,0 +1,1003 @@
 +/*
 + * Lantiq SoC SPI controller
 + *
@@ -667,10 +667,22 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
 +static void ltq_spi_rxreq_set(struct ltq_spi *hw)
 +{
 +      u32 rxreq, rxreq_max, rxtodo;
++      u32 fstat, fifo_fill;
 +
 +      rxtodo = ltq_spi_reg_read(hw, LTQ_SPI_RXCNT) & LTQ_SPI_RXCNT_TODO_MASK;
 +
 +      /*
++       * Check if there is remaining data in the FIFO before starting a new
++       * receive request. The controller might have processed some more data
++       * since the last FIFO poll.
++       */
++      fstat = ltq_spi_reg_read(hw, LTQ_SPI_FSTAT);
++      fifo_fill = ((fstat >> LTQ_SPI_FSTAT_RXFFL_SHIFT)
++                      & LTQ_SPI_FSTAT_RXFFL_MASK);
++      if (fifo_fill)
++              return;
++
++      /*
 +       * In RX-only mode the serial clock is activated only after writing
 +       * the expected amount of RX bytes into RXREQ register.
 +       * To avoid receive overflows at high clocks it is better to request