what is the reason for this mmc reading in linux [closed]

Question

what is the reason for this mmc reading problem in linux ..? please help to solve this...? please check my kernel booting log below help me to solve this..

I have enabled the relevant drivers for mmc compiled and booted with with newly created kernel image I am getting the kernel boot loogs as shown below

mmc0: card lacks mandatory switch function, performance might suffer.           
mmc0: host does not support reading read-only switch. assuming write-enable.    
mmc0: new SD card at address b368                                               
mmcblk0: mmc0:b368 SMI-S 8.00 MiB                                               
 mmcblk0:                                                                       
mmcblk0: retrying using single block read                                       
mmcblk0: error -110 transferring data, sector 0, nr 8, card status 0xb00        
end_request: I/O error, dev mmcblk0, sector 0                                   
mmcblk0: error -110 sending read/write command, response 0xb00, card status 0x40
end_request: I/O error, dev mmcblk0, sector 1                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 2                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 3                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 4                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 5                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 6                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 7                                   
Buffer I/O error on device mmcblk0, logical block 0                             
mmcblk0: retrying using single block read                                       
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 0                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 1                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 2                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 3                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 4                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 5                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 6                                   
mmcblk0: error -110 sending read/write command, response 0x400b00, card status 0
end_request: I/O error, dev mmcblk0, sector 7                                   
Buffer I/O error on device mmcblk0, logical block 0                             
unable to read partition table

Answer 1

Error -110 means timeout. Basically, your MMC controller is not able to talk correctly with your SD card. It usually happens when your card is not correctly inserted in the slot (for example the spring is pushing back your card too far) or maybe you are using a micro SD card and it is not correctly inserted in the SD card adapter. Want can also happen is that your SD card adapter is slightly broken and some connections are not correctly made (e.g. your card has negotiated 4 bits mode and some lines are in fact not connected).