i2c: OMAP3: Better noise suppression for fast/standard modes
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>
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index a879e4b..c73475d 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -333,8 +333,18 @@
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 */