* [U-Boot] I2C source clock frequency on MPC8544
@ 2008-09-25 13:20 Wolfgang Grandegger
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From: Wolfgang Grandegger @ 2008-09-25 13:20 UTC (permalink / raw)
To: u-boot
Hello,
the I2C source clock frequency for the MPC8544 is determined in
cpu/mpc85xx/speed.c:
#elif defined(CONFIG_MPC8544)
/*
* On the 8544, the I2C clock is the same as the SEC clock. This can be
* either CCB/2 or CCB/3, depending on the value of cfg_sec_freq. See
* 4.4.3.3 of the 8544 RM. Note that this might actually work for all
* 85xx, but only the 8544 has cfg_sec_freq, so it's unknown if the
* PORDEVSR2_SEC_CFG bit is 0 on all 85xx boards that are not an 8544.
*/
if (gur->pordevsr2 & MPC85xx_PORDEVSR2_SEC_CFG)
gd->i2c1_clk = sys_info.freqSystemBus / 3;
else
gd->i2c1_clk = sys_info.freqSystemBus / 2;
On our MPC8544 the MPC85xx_PORDEVSR2_SEC_CFG is set and the
diver 3 therefore used. But that seems to be wrong. Measurements show,
that the used divider is 2. Any idea what's going wrong? Is there an
errata for the MPC8544?
Wolfgang.
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2008-09-25 13:20 [U-Boot] I2C source clock frequency on MPC8544 Wolfgang Grandegger
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