On Wed, Jan 28, 2015 at 9:52 AM, Stefan Wahren <stefan.wah...@i2se.com> wrote: > Hi, > > Am 28.01.2015 um 04:36 schrieb Zhi Li: >> On Tue, Jan 27, 2015 at 7:51 PM, Mike Turquette <mturque...@linaro.org> >> wrote: >>> Quoting Marek Vasut (2015-01-21 15:39:01) >>>> On Wednesday, January 21, 2015 at 05:16:03 PM, Zhi Li wrote: >>>>> On Sun, Dec 28, 2014 at 4:26 AM, Stefan Wahren <stefan.wah...@i2se.com> >>>>> wrote: >>>>>> According to i.MX23 and i.MX28 reference manual the fractional >>>>>> clock control registers must be addressed by byte instructions. >>>>> I don't think mx23 and mx28 have such limitation. I will double check >>>>> with IC team about this. >>>>> RTL is generated from a xml file. All registers implement is unified. >>>>> I don't think only clock control register have such limitation and >>>>> other registers not. >>>> Hi, >>>> >>>> Section 10.8.24 in the MX28 datasheet (Fractional Clock Control Register 0) >>>> states otherwise, but maybe the documentation is simply not matching the >>>> silicon. >>>> >>>> Here's a quote: >>>> " >>>> This register controls the 9-phase fractional clock dividers. The >>>> fractional >>>> clock frequencies are a product of the values in these registers. NOTE: >>>> This >>>> register can only be addressed by byte instructions. Addressing word or >>>> half- >>>> word are not allowed. >>>> " >>>> >>>> I also recall seeing weird behavior when these registers were accessed by >>>> word >>>> access in U-Boot, so I believe the datasheet is correct. >>> Hi Frank, >>> >>> Are you satisfied with this patch? >> I asked IC designer about this. >> They will check RTL code. >> I will check their status again. >> Our released BSP code used 32bit WORD access. > > i want to point out that the 32bit WORD is divided in 4 parts (IO0FRAC, > IO1FRAC, EMIFRAC, CPUFRAC). Yes, it's true that BSP code access the > register as 32bit, but it's never modify the complete 32bit at once just > only 1 part (8bit) at a time. > > So here is my theory about Fractional Clock Control Register: > > Reading as 32bit WORD => safe > Modify only 1 part (8bit) of the 32bit WORD => safe > Modify more than 1 part of the 32bit WORD => unsafe !!!
Yes, it is align with what I get from IC designer. best regards Frank Li > > Best regards > Stefan > >> >> best regards >> Frank Li >>> Regards, >>> Mike >>> >>>> Best regards, >>>> Marek Vasut > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
