On Thu, Sep 15, 2011 at 10:07 AM, Marek Vasut <marek.va...@gmail.com> wrote: > On Thursday, September 15, 2011 03:43:42 AM Jason Hui wrote: >> On Thu, Sep 15, 2011 at 3:39 AM, Marek Vasut <marek.va...@gmail.com> wrote: >> > On Friday, July 29, 2011 08:55:14 AM Jason Hui wrote: >> >> Hi, Marek, >> >> >> >> On Thu, Jul 14, 2011 at 5:58 AM, Marek Vasut <marek.va...@gmail.com> >> >> wrote: >> >> > Rewrite the mxc_i2c driver. >> >> > * This version is much closer to Linux implementation. >> >> > * Fixes IPG_PERCLK being incorrectly used as clock source >> >> > * Fixes behaviour of the driver on iMX51 >> >> > * Clean up coding style a bit ;-) >> >> >> >> why you change i2c clock from IPG_PERCLK to IPG_CLK? >> >> >> >> [...] >> > >> > Ok, I investigated a bit deeper and I suspect the clock.c is the culprit. >> > >> > Apparently, the PERCLK doesn't run at the frequency the clock.c reports >> > it runs on. Therefore, the i2c miscalculates the divider etc -- falling >> > crap model (waterfall model). >> >> But apparently, the i2c function clock should be IPG_PERCLK not IPG >> clock. And Linux also fix it already. > > Then there's bulls**t in your mx51 and mx53 datasheet or what ?
Please refer to MCIMX51RM.PDF, page 305, Table 7-41. PERCLK-dependent Module Clock Sources PERCLK-dependent Module Clocks Associated CCGR Register uart1_perclk CCGR1 uart2_perclk uart3_perclk i2c1 clocks i2c2 clocks epit1_highfreq CCGR2 epit2_highfreq pwm1_highfreq pwm2_highfreq gpt_highfreq owire clocks > besides, PERCLK > is faster than IPGCLK on MX51 so it makes even less sense! I don't think PERCLK is always faster than IPG clock, it's configurable. please refer to MCIMX51RM.PDF, page 307. >Can you please talk > to the HW guys or whatever to clear this once and for all ? I smell noone > really > knows where the clock are sourced from and all this crap is just blind > guessing. I have asked the IC module owner again. It confirms that I2C function clock is ipg_perclk. Jason > _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
