On Fri, Sep 6, 2019 at 2:19 PM Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > > On Fri, 6 Sep 2019 at 11:14, Belisko Marek <marek.belisko@xxxxxxxxx> wrote: > > > > Hi, > > > > I'm trying to get some insights about how to debug emmc speed issue. > > We're using board with am437x CPU using mainline 4.12 kernel (added > > only devicetree for our custom board). eMMC is 8bit connect (using > > sandisk SDINBDG4-8G-I1 chip). > > > > Issue is that when copying data from SD card to eMMC we get throughput > > only ~300kB/s (it should be bit higher IIRC). I'm just looking for > > some advice what to check and how to find out where issue can be > > (still unsure if SW or HW). Thanks a lot. > > Mount debugfs and look at the ios node for the mmc host in question. > There is information about clocks, busdwidth, etc. Thanks for info. From below it looks quite ok: clock: 52000000 Hz vdd: 21 (3.3 ~ 3.4 V) bus mode: 2 (push-pull) chip select: 0 (don't care) power mode: 2 (on) bus width: 3 (8 bits) timing spec: 1 (mmc high-speed) signal voltage: 0 (3.30 V) driver type: 0 (driver type B) compared to gumstix poblano (same cpu): cat /sys/kernel/debug/mmc1/ios clock: 50000000 Hz vdd: 21 (3.3 ~ 3.4 V) bus mode: 2 (push-pull) chip select: 0 (don't care) power mode: 2 (on) bus width: 2 (4 bits) timing spec: 2 (sd high-speed) signal voltage: 0 (3.30 V) driver type: 0 (driver type B) difference is in bus width (I'm confused as poblano according dts + schematics should also have 8 bit interface) and timing spec are different for my case. Anything else I can check? Thanks. > > Kind regards > Uffe BR, marek
