DMA for Ricoh SD card reader on Lenovo laptops

If you have Lenovo laptop with Ricoh SD card reader like this:

lenovo greg # lspci -v |grep Ricoh
05:06.1 SD Host controller: Ricoh Co Ltd R5C822 SD/SDIO/MMC/MS/MSPro Host Adapter (rev 19)
05:06.2 System peripheral: Ricoh Co Ltd R5C592 Memory Stick Bus Host Adapter (rev 0a)
05:06.3 System peripheral: Ricoh Co Ltd xD-Picture Card Controller (rev 05)

You noticed that copying from SD card to disk takes much more time and cpu usage then on Windows. I tired to find out what is the reason. I’m use to that performance of my Linux box is better then windows. I found it that main problem is using by Ricoh PIO instead of DMA access. It causes high cpu usage and slow data transfer. You can probably check it: Continue reading