@jyijyi
PNY 4GB SD card supplied with MangOH Green board also show the same error in a MangOH red Revision 6 board:
root@swi-mdm9x28-wp:~# dmesg | grep mmc
[ 0.830606] sdhci_msm 7864900.sdhci: No vmmc regulator found
[ 0.830622] sdhci_msm 7864900.sdhci: No vqmmc regulator found
[ 0.831034] mmc0: SDHCI controller on 7864900.sdhci [7864900.sdhci] using 32- bit ADMA in legacy mode
[ 0.924502] mmc0: new ultra high speed SDR50 SDHC card at address 0001
[ 0.925224] mmcblk0: mmc0:0001 0000 3.72 GiB
[ 0.926387] mmc0: data txfr (0x00200000) error: -84 after 0 ms
[ 0.926404] sdhci: =========== REGISTER DUMP (mmc0)===========
[ 0.926787] mmc0: clk: 100000000 clk-gated: 0 claimer: mmcqd/0 pwr: 12 host-> irq = 8192
[ 0.926797] mmc0: rpmstatuspltfm (0:1:0)
[ 0.926924] mmcblk0: response CRC error sending r/w cmd command, card status 0x900
[ 0.927385] mmc0: data txfr (0x00200000) error: -84 after 0 ms
[ 0.927400] sdhci: =========== REGISTER DUMP (mmc0)===========
[ 0.927779] mmc0: clk: 100000000 clk-gated: 0 claimer: mmcqd/0 pwr: 12 host-> irq = 8192
[ 0.927789] mmc0: rpmstatuspltfm (0:1:0)
[ 0.927915] mmcblk0: error -84 transferring data, sector 0, nr 8, cmd respons e 0x900, card status 0xb00
[ 1.005633] mmc0: mmc_resume_clk_scaling: no devfreq is assosiated with this device
[ 1.005648] mmc0: mmc_sd_power_restore: fail to resume clock scaling (-1)
[ 1.005659] mmc0: mmc_blk_reset: failed to reset -1
[ 1.005674] blk_update_request: I/O error, dev mmcblk0, sector 0
[ 1.005688] Buffer I/O error on dev mmcblk0, logical block 0, async page read
[ 1.006358] mmcblk0: response CRC error sending r/w cmd command, card status 0x900
[ 1.006881] mmcblk0: error -84 transferring data, sector 0, nr 8, cmd respons e 0x900, card status 0xb00
[ 1.006898] blk_update_request: I/O error, dev mmcblk0, sector 0
[ 1.006911] Buffer I/O error on dev mmcblk0, logical block 0, async page read
[ 1.006951] mmcblk0: unable to read partition table
[ 39.073717] mmc_sd_detect(mmc0): Unable to re-detect card (-110)
[ 39.074439] mmc0: card 0001 removed
Usually the cards are read well at High speed not sure why the mmc driver is selecting UHS SDR50 speed?
can you suggest how to set the speed to high speed in the driver?