What is maximum speed in serial download mode on imx8mq

[ranjitsinh_rathod]

Hi there,

I am trying to flash emmc using serial download mode. Below are my observations related to speed of serial download mode.

1) 31248754032 Bytes image is taking 1787 seconds which is 16.67 MB/seconds

2) 31248754032 Bytes image is taking 1778 seconds which is 16.76 MB/seconds

3) 31248754032 Bytes image is taking 1767 seconds which is 16.86 MB/seconds

As per the RM, the ROM code is using USB OTG1 in high-speed mode and so the theoretical speed would be around 480 Mbps (60 MBps). But in the case of iMX8MQ, I am observing an average speed which is around 16.76 MBps.

Can someone suggest to me how can I increase the speed or what is the maximum speed supported by imx8mq in serial download mode?

Many Thanks,

Ranjitsinh Rathod

[jamesbone]

You are correct the download speed of the Serial Download Mode it is  60MBps or  480Mbps. Since we it is the standard of the USB port. But I do not how are you measure the speed, since it also depends on the media that you are flashing, you need to check if the eMMC supports that speed of flashing.  The media always it is slower.

[ranjitsinh_rathod]

Hi Jamesbone,

I have already checked my emmc speed and it seems it is running in HS400 mode and so practically data transfer rate for this mode is  400 MB/s. Please find below information regarding emmc.

u-boot=> mmcinfo
Device: FSL_SDHC
Manufacturer ID: 45
OEM: 100
Name: DG403
Bus Speed: 200000000
Mode : HS400 (200MHz)
Rd Block Len: 512
MMC version 5.1
High Capacity: Yes
Capacity: 29.1 GiB
Bus Width: 8-bit DDR
Erase Group Size: 512 KiB
HC WP Group Size: 8 MiB
User Capacity: 29.1 GiB WRREL
Boot Capacity: 4 MiB ENH
RPMB Capacity: 4 MiB ENH

Thanks,

Ranjitsinh Rathod