[meta-xilinx] Really bad SD/eMMC performance after upgrading 2018.1 to 2018.3

[Mike Looijmans]

It's definitely the PMU or ATF that causes this.

If I use the 2018.1 ATF and PMU, the SDIO controller performance is okay with 
either the 2018.1 or 2018.3 kernel. With the 2018.3 release of PMU and ATF, 
the SD performance is horrible. I also noticed it stopped USB from working.

Maybe something in the PMU-kernel or ATF-kernel interface has changed and e.g. 
clock settings aren't properly communicated?

Mike

On 21-03-19 14:03, Mike Looijmans wrote:
> The SD and eMMC controller has become terribly slow in 2018.3:
> 
> # echo 3 > /proc/sys/vm/drop_caches
> 
> # dd if=/dev/mmcblk0 of=/dev/null bs=1M count=20
> 20+0 records in
> 20+0 records out
> 20971520 bytes (20.0MB) copied, 4.972666 seconds, 4.0MB/s
> 
> # dd if=/dev/mmcblk1 of=/dev/null bs=1M count=20
> 20+0 records in
> 20+0 records out
> 20971520 bytes (20.0MB) copied, 38.899436 seconds, 526.5KB/s
> 
> 
> This used to be over 160MB/s for the eMMC (mmcblk0) and over 20 MB/s for the
> SD card (mmcblk0) with the 2018.1 kernel and bootloader.
> 
> This is only in Linux, the bootloader still reads at about 10MB/s from the SD
> card. So apparently the clocks are set up okay.
> 
> According to the kernel, the clocks and interface are running at full speed:
> 
> # cat /sys/kernel/debug/mmc0/ios
> clock:          200000000 Hz
> actual clock:   200000000 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:    9 (mmc HS200)
> signal voltage: 1 (1.80 V)
> driver type:    0 (driver type B)
> 
> # cat /sys/kernel/debug/mmc1/ios
> clock:          50000000 Hz
> actual 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)
> 
> 
> Any insights?
>