The patch below does not apply to the 3.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 9d239d353c319f9ff884c287ce47feb7cdf60ddc Mon Sep 17 00:00:00 2001
From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Date: Wed, 25 Feb 2015 11:39:36 +0200
Subject: [PATCH] spi: dw: revisit FIFO size detection again
The commit d297933cc7fc (spi: dw: Fix detecting FIFO depth) tries to fix the
logic of the FIFO detection based on the description on the comments. However,
there is a slight difference between numbers in TX Level and TX FIFO size.
So, by specification the FIFO size would be in a range 2-256 bytes. From TX
Level prospective it means we can set threshold in the range 0-(FIFO size - 1)
bytes. Hence there are currently two issues:
a) FIFO size 2 bytes is actually skipped since TX Level is 1 bit and could be
either 0 or 1 byte;
b) FIFO size is incorrectly decreased by 1 which already done by meaning of
TX Level register.
This patch fixes it eventually right.
Fixes: d297933cc7fc (spi: dw: Fix detecting FIFO depth)
Reviewed-by: Axel Lin <axel.lin@xxxxxxxxxx>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 5a97a62b298a..4847afba89f4 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -621,14 +621,14 @@ static void spi_hw_init(struct device *dev, struct dw_spi *dws)
if (!dws->fifo_len) {
u32 fifo;
- for (fifo = 2; fifo <= 256; fifo++) {
+ for (fifo = 1; fifo < 256; fifo++) {
dw_writew(dws, DW_SPI_TXFLTR, fifo);
if (fifo != dw_readw(dws, DW_SPI_TXFLTR))
break;
}
dw_writew(dws, DW_SPI_TXFLTR, 0);
- dws->fifo_len = (fifo == 2) ? 0 : fifo - 1;
+ dws->fifo_len = (fifo == 1) ? 0 : fifo;
dev_dbg(dev, "Detected FIFO size: %u bytes\n", dws->fifo_len);
}
}
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html