>>>>> >>>>>> -----Original Message----- >>>>>> From: Chris Ball [mailto:cjb@xxxxxxxxxx] >>>>>> Sent: Wednesday, September 12, 2012 4:59 AM >>>>>> To: Kumar Gala >>>>>> Cc: Huang Changming-R66093; linuxppc-dev@xxxxxxxxxxxxxxxx list; >>>>>> linux- mmc@xxxxxxxxxxxxxxx; Anton Vorontsov >>>>>> Subject: Re: [PATCH 2/3] powerpc/esdhc: add property to disable the >>>>>> CMD23 >>>>>> >>>>>> Hi, >>>>>> >>>>>> On Tue, Sep 11 2012, Kumar Gala wrote: >>>>>>> thanks for the info. Do you know what's required on controller >>>>>>> side to handle cards that support CMD23? >>>>>>> >>>>>>> I'm trying to figure out if older controller's on FSL SoCs are >>>>>>> missing some feature to allow CMD23 to work (vs Auto-CMD23). >>>>>> >>>>>> It seems plausible that it's just not implemented on these >> controllers. >>>>>> It's a little strange, since the command's been specified for so >>>>>> long and we haven't seen any other controllers with problems. The >>>>>> patch would be correct if this is true. >>>>>> >>>>> >>>>> I didn't find any description about it, but after testing on FSL >>>> silicones, I got this result: >>>>> Some silicones support this command, and some silicones don't >>>>> support >>>> it, which will cause I/O error. >>>> >>>> Can you list out which SoCs support it and which don't. Having this >>>> list will be useful in understanding which controller versions >> supported it. >>>> >>> P1020, p1021, p1022, p1024, p1015 and p4080 can't support it. >>> Mpc8536, p2020, and the other current DPAA silicon (e.g. p5020, p3041) >> support it. >> >> Based on this, why don't we use the HOSTVER register to detect instead of >> device tree: >> >> >> #define FSL_SDHC_VER_1_0 0x00 >> #define FSL_SDHC_VER_1_1 0x01 >> #define FSL_SDHC_VER_2_0 0x10 >> #define FSL_SDHC_VER_2_1 0x11 >> #define FSL_SDHC_VER_2_2 0x12 >> #define FSL_SDHC_VER_2_3 0x13 >> >> unsigned int vendor_version; >> >> vendor_version = sdhci_readw(host, SDHCI_HOST_VERSION); vendor_version = >> (vendor_version & SDHCI_VENDOR_VER_MASK) >> SDHCI_VENDOR_VER_SHIFT; >> >> if ((vendor_version == FSL_SDHC_VER_1_1) || (vendor_version == >> FSL_SDHC_VER_2_2)) >> host->quirks2 |= SDHCI_QUIRK2_HOST_NO_CMD23; >> > > I once thought about it, but if the future silicon does not support this feature, > then we continue to modify these codes for new silicon? Yes, but it seems extremely unlikely that future versions of the controller will remove this feature now that it exists. - k-- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
