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spi: can use a tx threshold of 50%

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The TX fifo threshold is pretty arbitrary.
Set this too big and too many interrupts will occur
for no good reason. Set it too small, and latency
in the SPI transactions is introduced. User's will probably
have to tune this per their application and SPI frequency, etc.
I think setting this to 50% is a good guess for now.

Change-Id: Ib325d40bc7ee10473d99443b3b3cd00fd6e4b95f
Signed-off-by: Chuck Jordan <cjordan@synopsys.com>
This commit is contained in:
Chuck Jordan 2016-05-25 16:43:31 -07:00 committed by Anas Nashif
parent fe5aa9f6ae
commit d11ed0b13e
1 changed files with 1 additions and 1 deletions
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2
drivers/spi/spi_dw.h
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@ -176,7 +176,7 @@ struct spi_dw_data {
/* Threshold defaults */
#define DW_SPI_FIFO_DEPTH CONFIG_SPI_DW_FIFO_DEPTH
#define DW_SPI_TXFTLR_DFLT ((DW_SPI_FIFO_DEPTH*5)/8)
#define DW_SPI_TXFTLR_DFLT ((DW_SPI_FIFO_DEPTH*1)/2) /* 50% */
#define DW_SPI_RXFTLR_DFLT ((DW_SPI_FIFO_DEPTH*5)/8)
/* Interrupt mask (IMR) */