public inbox for u-boot@lists.denx.de
 help / color / mirror / Atom feed
* [U-Boot] I2C source clock frequency on MPC8544
@ 2008-09-25 13:20 Wolfgang Grandegger
  0 siblings, 0 replies; only message in thread
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.

^ permalink raw reply	[flat|nested] only message in thread

only message in thread, other threads:[~2008-09-25 13:20 UTC | newest]

Thread overview: (only message) (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2008-09-25 13:20 [U-Boot] I2C source clock frequency on MPC8544 Wolfgang Grandegger

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox