The patch titled
atmel_spi: reload RCR before TCR
has been added to the -mm tree. Its filename is
atmel_spi-reload-rcr-before-tcr.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: atmel_spi: reload RCR before TCR
From: Rini van Zetten <rini@xxxxxxxx>
We have a wifi module connected to the spi bus and got sometimes FIFO
overrun errors on the spi bus.
After some investigation i found that the driver loads the TCR (transmit
count) register before the RCR (receive count). When the transfer list is
not empty the atmel_spi_next_message is called while tx and rx are enabled.
As soon as the TCR is loaded, hardware starts transfer and causes a rx
fifo overrun because the RCR is not loaded yet.
Load the RCR before the TCR. After this patch the fifo overrun disapears
at out setup.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@xxxxxxxxx>
Signed-off-by: Rini van Zetten <rini@xxxxxxxx>
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/spi/atmel_spi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN drivers/spi/atmel_spi.c~atmel_spi-reload-rcr-before-tcr drivers/spi/atmel_spi.c
--- a/drivers/spi/atmel_spi.c~atmel_spi-reload-rcr-before-tcr
+++ a/drivers/spi/atmel_spi.c
@@ -195,8 +195,8 @@ static void atmel_spi_next_xfer(struct s
xfer, xfer->len, xfer->tx_buf, xfer->tx_dma,
xfer->rx_buf, xfer->rx_dma, spi_readl(as, IMR));
- spi_writel(as, TCR, len);
spi_writel(as, RCR, len);
+ spi_writel(as, TCR, len);
spi_writel(as, PTCR, SPI_BIT(TXTEN) | SPI_BIT(RXTEN));
}
_
Patches currently in -mm which might be from rini@xxxxxxxx are
atmel_spi-reload-rcr-before-tcr.patch
-
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