Hello, I have a Dell Latitude E7450 with a O2 Micro, SD/MMC Card Reader [1217:8520] card reader. When I insert my Sandisk ultra 64GB microSD (with a SD card adapter) I get the following errors. Dmesg output after I insert the SD card: [ 306.054203] sdhci: Timeout waiting for Buffer Read Ready interrupt during tuning procedure, falling back to fixed sampling clock [ 306.055982] mmc0: tuning execution failed [ 306.055987] mmc0: error -5 whilst initialising SD card [ 306.466185] sdhci: Timeout waiting for Buffer Read Ready interrupt during tuning procedure, falling back to fixed sampling clock [ 306.467964] mmc0: tuning execution failed [ 306.467970] mmc0: error -5 whilst initialising SD card [ 306.890205] sdhci: Timeout waiting for Buffer Read Ready interrupt during tuning procedure, falling back to fixed sampling clock [ 306.891993] mmc0: tuning execution failed [ 306.892005] mmc0: error -5 whilst initialising SD card [ 307.330197] sdhci: Timeout waiting for Buffer Read Ready interrupt during tuning procedure, falling back to fixed sampling clock [ 307.331980] mmc0: tuning execution failed [ 307.331990] mmc0: error -5 whilst initialising SD card I used the latest mainline kernel available to me [1] $ uname -a Linux cosmo 4.4.0-040400rc4-generic #201512061930 SMP Mon Dec 7 00:32:31 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux It was working fine for kernel versions older than 4.1.8. I did a bisection and here is the first bad commit > e6c69099f63c84e1825c0f742a76ff4a8afeaa9b is the first bad commit > commit e6c69099f63c84e1825c0f742a76ff4a8afeaa9b > Author: Adam Lee <adam.lee@xxxxxxxxxxxxx> > Date: Mon Aug 3 14:33:28 2015 +0800 > > mmc: sdhci-pci: set the clear transfer mode register quirk for O2Micro > > commit 143b648ddf1583905fa15d32be27a31442fc7933 upstream. > > This patch fixes MMC not working issue on O2Micro/BayHub Host, which > requires transfer mode register to be cleared when sending no DMA > command. > > Signed-off-by: Peter Guo <peter.guo@xxxxxxxxxxxxxx> > Signed-off-by: Adam Lee <adam.lee@xxxxxxxxxxxxx> > Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> I originally logged this issue to the Ubuntu bug tracker[2], but it appears to be an upstream issue and so I was instructed to report here. Please note that I use the latest Bios version for the model. $ sudo dmidecode -s bios-version;sudo dmidecode -s bios-release-date A08 10/28/2015 [1] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.4-rc4-wily/ [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1523178 Thanks, Alex
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