On Tue, May 5, 2009, Jarkko Lavinen wrote: > On Tue, Apr 21, 2009 at 09:39:22AM +0200, ext Gadiyar, Anand wrote: > > From: Anand Gadiyar <gadiyar@xxxxxx> > > > > OMAP: HSMMC: Do not enable buffer ready interrupt if using DMA > > > > This considerably reduces the number of interrupts during a transfer > > and ought to result in some power saving. > > I tried the patch with reading from the raw mmc block device to > /dev/null with dd (with bs 32k and 1M). I cannot see any > difference in interrupt count from /proc/interrupts or in read > speed. At least the patch works. Cpu was 34340es3. > > I also trid without the patch just disabling the Buffer > Read/write Ready bits from INT_EN_MASK which is then written to > both MMCHS_IE and MMCHS_ISE. Still no change in read speed nor > mmc irq count. > > Cheers > Jarkko Lavinen I discovered this while doing MMC writes. I did not check if there was any difference during a read. I notice you have only tested with MMC reads. Here's what I get with and without the patch. - Anand Without patch / # mount -t vfat /dev/mmcblk0 /mnt/mmc / # cat /proc/interrupts | grep mmc 83: 90 INTC mmc0 384: 1 twl4030 mmc0 / # dd if=/dev/zero of=/mnt/mmc/32kbs.txt bs=32k count=1000 1000+0 records in 1000+0 records out / # cat /proc/interrupts | grep mmc 83: 3760 INTC mmc0 384: 1 twl4030 mmc0 / # dd if=/dev/zero of=/mnt/mmc/1Mbs.txt bs=1M count=32 32+0 records in 32+0 records out / # cat /proc/interrupts | grep mmc 83: 7570 INTC mmc0 384: 1 twl4030 mmc0 / # ls -l /mnt/mmc -rwxr-xr-x 1 root root 33554432 Dec 31 18:03 1Mbs.txt -rwxr-xr-x 1 root root 32768000 Dec 31 18:03 32kbs.txt / # umount /mnt/mmc With patch / # mount -t vfat /dev/mmcblk0 /mnt/mmc / # cat /proc/interrupts | grep mmc 83: 67 INTC mmc0 384: 0 twl4030 mmc0 / # dd if=/dev/zero of=/mnt/mmc/32kbs.txt bs=32k count=1000 1000+0 records in 1000+0 records out / # cat /proc/interrupts | grep mmc 83: 3103 INTC mmc0 384: 0 twl4030 mmc0 / # dd if=/dev/zero of=/mnt/mmc/1Mbs.txt bs=1M count=32 32+0 records in 32+0 records out / # cat /proc/interrupts | grep mmc 83: 6170 INTC mmc0 384: 0 twl4030 mmc0 / # ls -l /mnt/mmc -rwxr-xr-x 1 root root 33554432 Dec 31 18:01 1Mbs.txt -rwxr-xr-x 1 root root 32768000 Dec 31 18:00 32kbs.txt / # umount /mnt/mmc-- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
