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BUG REPORT: cpu consumption is too high when write SD card using davinci_mmc.c

Test 1
 - EVMDM365 from Spectrum Digital
 - linux-2.6.32-rc2 from DVSDK v3.10 (using davinci_mmc.c)
 - Sandisk 2GB card
 - 25MHz bus freq
 - 4bit bus width
 - DMA enabled
 - dd if=/dev/zero of=/dev/mmcblk0p1 bs=1M
 - top -d 1
 - mmcqd max cpu consumption is 40~50%!!!


Test 2
 - EVMDM6446 from Spectrum Digital
 - linux-2.6.10_mvl401 from LSP v1.10 patch47 (using davinci_mmc.c), and change mmc_blk_issue_rq to use MMC_WRITE_MULTIPLE_BLOCK (instead of MMC_WRITE_BLOCK)
 - ...
 - mmcqd max cpu consumption is 70%!!!


Test 3
 - EVMDM6446 from Spectrum Digital
 - linux-2.6.10_mvl401 from LSP v1.10 patch50 (using drivers/sdio)
 - ...
 - keventd+irq max cpu consumption is 10%!!


Why cpu consumption is so high when use davinci_mmc.c?

How can we fix it to achive small cpu consumption like drivers/sdio does?

Is there any effort to port drivers/sdio to DVSDK v2.10 (for DM365)?


Thanks
Eddy