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| author | Stefan Roese <sr@denx.de> | 2015-03-18 09:30:54 +0100 |
|---|---|---|
| committer | Heiko Schocher <hs@denx.de> | 2015-03-18 09:48:42 +0100 |
| commit | f582a1583b2c7ae91737f3b1a0b850e7f4ef68bb (patch) | |
| tree | 1301c2bbd5c9f0a2f1bdadfdfdd31c0b0c1b5314 /drivers/i2c/mvtwsi.c | |
| parent | e6fbc3e4f1f2f974ec8efe9d52cfcb22b87f6294 (diff) | |
| download | talos-obmc-uboot-f582a1583b2c7ae91737f3b1a0b850e7f4ef68bb.tar.gz talos-obmc-uboot-f582a1583b2c7ae91737f3b1a0b850e7f4ef68bb.zip | |
i2c: mvtwsi: Fix problem with baud rate calculation
The current implementation for baudrate calculation is incorrect.
This part from the formula:
"2 ^ (n + 1)" is not equivalent to (1 << n) but to (2 << n)!
This patch fixes this and moves this calculation to a function instead of using a macro.
This new function is taken from the Linux kernel.
This was detected and tested on the Marvell Armada A38x DB-88F6820-GP eval board.
Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Prafulla Wadaskar <prafulla@marvell.com>
Cc: Luka Perkov <luka.perkov@sartura.hr>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Ian Campbell <ijc@hellion.org.uk>
Cc: Heiko Schocher <hs@denx.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Diffstat (limited to 'drivers/i2c/mvtwsi.c')
| -rw-r--r-- | drivers/i2c/mvtwsi.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/drivers/i2c/mvtwsi.c b/drivers/i2c/mvtwsi.c index 9b2ca1e81b..6f6edd5e51 100644 --- a/drivers/i2c/mvtwsi.c +++ b/drivers/i2c/mvtwsi.c @@ -228,13 +228,14 @@ static int twsi_stop(int status) return status; } -/* - * Ugly formula to convert m and n values to a frequency comes from - * TWSI specifications - */ - -#define TWSI_FREQUENCY(m, n) \ - (CONFIG_SYS_TCLK / (10 * (m + 1) * (1 << n))) +static unsigned int twsi_calc_freq(const int n, const int m) +{ +#ifdef CONFIG_SUNXI + return CONFIG_SYS_TCLK / (10 * (m + 1) * (1 << n)); +#else + return CONFIG_SYS_TCLK / (10 * (m + 1) * (2 << n)); +#endif +} /* * Reset controller. @@ -266,7 +267,7 @@ static unsigned int twsi_i2c_set_bus_speed(struct i2c_adapter *adap, /* compute m, n setting for highest speed not above requested speed */ for (n = 0; n < 8; n++) { for (m = 0; m < 16; m++) { - tmp_speed = TWSI_FREQUENCY(m, n); + tmp_speed = twsi_calc_freq(n, m); if ((tmp_speed <= requested_speed) && (tmp_speed > highest_speed)) { highest_speed = tmp_speed; |
