Hi, with the current mainline 4.10-rc2 kernel, I can no longer boot from the eMMC on my i.MX6Q board. Details: The eMMC is a Micron MTFC4GACAJCN-1M WT but as the i.MX6Q only supports eMMC 4.41 features and we did not implement voltage switching from 3.3V to 1.8V or lower, I did add no-1-8-v; (but none of the mmc-ddr or mmc-hs options) to the device tree. The bus-width is 8. With 4.9 the board booted fine, now with the current mainline 4.10 tree, I get the following (repeating) errors at boot: [ 4.326834] Waiting for root device /dev/mmcblk0p2... [ 14.563861] mmc0: Timeout waiting for hardware cmd interrupt. [ 14.569619] sdhci: =========== REGISTER DUMP (mmc0)=========== [ 14.575461] sdhci: Sys addr: 0x4e726000 | Version: 0x00000002 [ 14.581300] sdhci: Blk size: 0x00000200 | Blk cnt: 0x00000001 [ 14.587140] sdhci: Argument: 0x00010000 | Trn mode: 0x00000013 [ 14.592979] sdhci: Present: 0x01fd8009 | Host ctl: 0x00000031 [ 14.598816] sdhci: Power: 0x00000002 | Blk gap: 0x00000080 [ 14.604654] sdhci: Wake-up: 0x00000008 | Clock: 0x0000001f [ 14.610493] sdhci: Timeout: 0x0000008f | Int stat: 0x00000000 [ 14.616332] sdhci: Int enab: 0x107f100b | Sig enab: 0x107f100b [ 14.622168] sdhci: AC12 err: 0x00000000 | Slot int: 0x00000003 [ 14.628007] sdhci: Caps: 0x07eb0000 | Caps_1: 0x0000a007 [ 14.633845] sdhci: Cmd: 0x00000d1a | Max curr: 0x00ffffff [ 14.639682] sdhci: Host ctl2: 0x00000000 [ 14.643611] sdhci: ADMA Err: 0x00000000 | ADMA Ptr: 0x4e6f7208 [ 14.649447] sdhci: =========================================== This repeats a few times, then more information is shown at the bottom: [ 86.893859] mmc0: Timeout waiting for hardware cmd interrupt. [ 86.899615] sdhci: =========== REGISTER DUMP (mmc0)=========== [ 86.905453] sdhci: Sys addr: 0x00000000 | Version: 0x00000002 [ 86.911291] sdhci: Blk size: 0x00000200 | Blk cnt: 0x00000001 [ 86.917129] sdhci: Argument: 0x00010000 | Trn mode: 0x00000013 [ 86.922967] sdhci: Present: 0x01fd8009 | Host ctl: 0x00000031 [ 86.928804] sdhci: Power: 0x00000002 | Blk gap: 0x00000080 [ 86.934642] sdhci: Wake-up: 0x00000008 | Clock: 0x0000001f [ 86.940479] sdhci: Timeout: 0x0000008f | Int stat: 0x00000000 [ 86.946316] sdhci: Int enab: 0x107f100b | Sig enab: 0x107f100b [ 86.952154] sdhci: AC12 err: 0x00000000 | Slot int: 0x00000003 [ 86.957992] sdhci: Caps: 0x07eb0000 | Caps_1: 0x0000a007 [ 86.963830] sdhci: Cmd: 0x00000d1a | Max curr: 0x00ffffff [ 86.969668] sdhci: Host ctl2: 0x00000000 [ 86.973596] sdhci: ADMA Err: 0x00000000 | ADMA Ptr: 0x00000000 [ 86.979433] sdhci: =========================================== [ 86.986356] mmc0: switch to bus width 8 ddr failed [ 86.991163] mmc0: error -110 whilst initialising MMC card [ 97.773859] mmc0: Timeout waiting for hardware cmd interrupt. -- After looking through the latest commits to mmc/core, I found the culprit: Commit e173f8911f091fa50ccf8cc1fa316dd5569bc470 ("mmc: core: Update CMD13 polling policy when switch to HS DDR mode") Reverting it fixes the problem. But I am unsure if that's the right course of action? Feel free to send me patches for testing! Regards, Clemens -- 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