Hi,

with commit 942b5fc0 the 8-bit data bus seems to work fine in U-Boot. However, I have one situation where I get transfer errors lateron in Linux. At the moment I suspect that this is rather a problem of the Linux driver, but I would like to make sure here first. My ZynqMP has an eMMC flash connected to SD0 and an SD-card to SD1. When I boot the device from SD-card and load a kernel ITB (tested both 4.14 and 5.4), I immediately get errors when writing to the eMMC flash in Linux:

print_req_error: I/O error, dev mmcblk0, sector 2048 Buffer I/O error on dev mmcblk0p1, logical block 0, lost sync page write mmc0: Got data interrupt 0x00000002 even though no data operation was in progress. mmc0: sdhci: ============ SDHCI REGISTER DUMP =========== mmc0: sdhci: Sys addr: 0x00000400 | Version: 0x00001002 mmc0: sdhci: Blk size: 0x00007200 | Blk cnt: 0x00000400 mmc0: sdhci: Argument: 0x00000000 | Trn mode: 0x00000033 mmc0: sdhci: Present: 0x1ff70000 | Host ctl: 0x0000003d mmc0: sdhci: Power: 0x0000000f | Blk gap: 0x00000080 mmc0: sdhci: Wake-up: 0x00000000 | Clock: 0x00000007 mmc0: sdhci: Timeout: 0x00000006 | Int stat: 0x00000000 mmc0: sdhci: Int enab: 0x02ff000b | Sig enab: 0x02ff000b mmc0: sdhci: AC12 err: 0x00000000 | Slot int: 0x00000000 mmc0: sdhci: Caps: 0x75ecc881 | Caps_1: 0x00002007 mmc0: sdhci: Cmd: 0x00000c1a | Max curr: 0x00000000 mmc0: sdhci: Resp[0]: 0x00000b00 | Resp[1]: 0x36475026 mmc0: sdhci: Resp[2]: 0x49533031 | Resp[3]: 0x00000900 mmc0: sdhci: Host ctl2: 0x0000008b mmc0: sdhci: ADMA Err: 0x00000000 | ADMA Ptr: 0x0000000000000000 mmc0: sdhci: ============================================

Interestingly, I can work-around this by just typing "mmc info" in the U-Boot console. As soon as some interaction with mmc0 happens in U-Boot , this problem disappears (i.e. anything that relies on the mmc layer to issue transfers to the eMMC flash). This did not happen before, when only a 4-bit data bus was supported. Also the latest commit e44c2bc on the Xilinx U-boot git repository does not solve this problem.

From my understanding, the Linux driver should be independent of the initialization done in U-Boot, right?

Does anyone have an idea or a comment to this? Did I miss anything?

Thanks, Benedikt