[PATCH v4] mmc: zynq: parse dt when probing

[Benedikt Grassl]

Hi Michal,

I just tried to check if the read performance acutally increased when
using an 8-bit data bus. As a quick test, I use the fatload command to
read a chunk of 1 GByte from an eMMC flash (generated with dd from
Linux). However, I don't see any difference at all:

mmc info
Device: mmc at ff160000
Manufacturer ID: 9d
OEM: 101
Name: IS016 
Bus Speed: 200000000
Mode: HS200 (200MHz)
Rd Block Len: 512
MMC version 5.0
High Capacity: Yes
Capacity: 14.6 GiB
Bus Width: 4-bit
(...)

fatload mmc 0 ${loadimage} test.img
1070579712 bytes read in 70458 ms (14.5 MiB/s)

With an 8-bit data bus:

mmcinfo 
Device: mmc at ff160000
Manufacturer ID: 9d
OEM: 101
Name: IS016 
Bus Speed: 200000000
Mode: HS200 (200MHz)
Rd Block Len: 512
MMC version 5.0
High Capacity: Yes
Capacity: 14.6 GiB
Bus Width: 8-bit
(...)

fatload mmc 0 ${loadimage} test.img
1070579712 bytes read in 70551 ms (14.5 MiB/s)

I wonder if the fatload command is the bottleneck here? Unfortunately
I'm working from home right now and don't have an oscilloscope at hand
to verify in hardware. Do you have any inputs on that?

Thanks,
Benedikt