On Wed, Jan 19, 2011 at 12:14:40PM +0900, Magnus Damm wrote: > Hi Simon, > > On Wed, Jan 19, 2011 at 9:09 AM, Simon Horman <horms@xxxxxxxxxxxx> wrote: > > Hi, > > > > I am currently interested in the read performance of the SDHI driver. ÂI > > ran the following tests on a Mackerel board using Linus's latest tree > > (6845a44a), which I believe has all of the outstanding patches from Arnd > > and Guennadi merged. > > Nice, thanks for testing this. > > > I have made the following crude performance measurements using > > several different cards. > > > > dd if=/dev/mmcblk1 of=/dev/null bs=512 count=100000 > > > > SD1.1: Â Â Â Â Â7.0 MB/s > > SD2.0: Â Â Â Â Â7.0 MB/s > > SDHC Class 2: Â 7.1 MB/s > > SDHC Class 10: Â7.2 MB/s > > > > Whereas I would expect something like: > > > > SD1.1 card: Â Â 12 MB/s > > SD2.0 card: Â Â 24 MB/s > > SDHC Class 2: Â 24 MB/s > > SDHC Class 10: ÂFaster? > > Please have a look at the clock frequency set by the SDHI MFD driver > (hclk), together with the tmio-mmc settings in tmio_mmc_set_clock(). > For the clock to be bumped up properly some capability/feature flags > may be needed: > > MMC_CAP_MMC_HIGHSPEED > MMC_CAP_SD_HIGHSPEED > > Not sure if they are set properly. Probably not. Actually this is one thing that I did check, sorry for not mentioning it. The clock does seem to be set correctly, to 50Mhz for the high-speed case, which iirc is everything except SD1.1. > > Possibly relevant portions of my .config are: > > > > CONFIG_MFD_SH_MOBILE_SDHI=y > > CONFIG_TMIO_MMC_DMA=y > > CONFIG_MMC_TMIO=y > > These two are also relevant: > > CONFIG_SH_DMAE=y > CONFIG_DMA_ENGINE=y > > DMA controller platform data is also needed, not sure the state of > your board. You can check out the counters in /proc/interrupts to see > if the DMA controller is active or not. Thanks! I have CONFIG_DMA_ENGINE but not CONFIG_SH_DMAE. -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
