I found my 4-bit connected eMMC chip wasn't working because barebox was trying to run it in 8-bit mode. I had the proper bus-width property in the device tree, but this doesn't work. The problem is that mci_of_parse() uses bus-width to _add_ 8-bit and/or 4-bit caps to the host. It doesn't remove any host_caps the driver already has set. So if the driver supports 8-bit but the DT bus-width is 4, you still get a driver that thinks 8-bit will work. You can see this in dw_mmc.c, dw_mmc_probe() sets: host->mci.host_caps = MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA then later mci_of_parse(&host->mci); return mci_register(&host->mci); The mci_of_parse call will not remove the 4 and 8 bits caps. There is the same problem in imx-esdhc.c. The other two users of mci_of_parse, mxs.c and tegra-sdmmc.c, don't have this problem, since they don't set any bus-width host_caps in the driver and depend on the DT or platform_data to have this info. With drivers split 50/50, which is the right way? Don't have the driver report what bits it supports and depend on the device tree to have that information? Or have of_mci_parse remove widths that aren't indicated as supported in the DT, so that the DT can remove widths the hardware indicates it supports. _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
