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i2c: OMAP3: Better noise suppression for fast/standard modes

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Use longer noise filter period for fast and standard mode. Based on an
earlier patch by Eero Nurkkala.

Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
This commit is contained in:
Aaro Koskinen 2009-05-27 17:54:46 +03:00 committed by Ben Dooks
parent baf46b4e37
commit 84bf2c868f
1 changed files with 12 additions and 2 deletions
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14
drivers/i2c/busses/i2c-omap.c
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@ -333,8 +333,18 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
if (cpu_is_omap2430() || cpu_is_omap34xx()) {
/* HSI2C controller internal clk rate should be 19.2 Mhz */
internal_clk = 19200;
/*
* HSI2C controller internal clk rate should be 19.2 Mhz for
* HS and for all modes on 2430. On 34xx we can use lower rate
* to get longer filter period for better noise suppression.
* The filter is iclk (fclk for HS) period.
*/
if (dev->speed > 400 || cpu_is_omap_2430())
internal_clk = 19200;
else if (dev->speed > 100)
internal_clk = 9600;
else
internal_clk = 4000;
fclk_rate = clk_get_rate(dev->fclk) / 1000;
/* Compute prescaler divisor */