"Timeout waiting for hardware interrupt" on Lenovo Thinkpad Tablet 10

["Sébastien Bourdeauducq" <sb@m-labs.hk>]

Hi,

Under Linux, the most annoying problem that the Lenovo Thinkpad Tablet
10 has is the unreliable eMMC.

I intermittently get an error "mmc0: Timeout waiting for hardware
interrupt" followed by a crash of the machine (when the eMMC is used as
rootfs).

I have been able to work around this issue with kernel 3.13.0 by passing
the debug_quirks2=0xc0 option to the sdhci module, which disables the
HS200 and DDR50 transfer modes. The read data rate (as measured by
hdparm -t) drops from 119MB/s to 42MB/s, but at least the computer no
longer crashes every 20 minutes and my files are not corrupted anymore.

Unfortunately, with more recent kernels such as 3.18.4, the sdhci module
(still with debug_quirks2=0xc0) appears to select another problematic
transfer mode. The read data rate jumps to 65MB/s and the bug manifests
itself again.

What changes in sdhci between 3.13.0 and 3.18.4 could cause that? I'd
like to be able to use the eMMC reliably at least at 42MB/s using recent
kernels, which hopefully will introduce fixes for the gazillion other
problems that this crippled machine has under Linux (absolutely nothing
works correctly except the CPU, display and USB).

Thanks,
Sébastien