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 !!! 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/
