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

[Mike Looijmans]

Have only tried the MPSoC.

I haven't tried the 7k yet with 2018.3, may get to that tomorrow. I 
suspect it's something with the PMU interface and/or clock dividers.


On 21-03-19 17:54, Peter Smith wrote:
> Mike, although I have not made any measurements I have noticed in the 
> last few days (coincidentally I have been doing a lot of work with a 
> ZCU102) that the SD interface seemed a bit slow. Are you seeing this on 
> Zynq 7K or US+ MPSoC?
> Best Regards
> Peter
> 
> 
> On Thu, 21 Mar 2019 at 16:38, Mike Looijmans <mike.looijmans at topic.nl 
> <mailto:mike.looijmans at topic.nl>> 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?
>     -- 
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-- 
Mike Looijmans