Apalis-TK1 LVDS drive strength not set by device tree

Technical Support
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1

Hi,

I have a couple of notes regarding the change:

https://git.toradex.com/cgit/linux-toradex.git/commit/?h=toradex_tk1_l4t_r21.7&id=ba01a34d91b3cc65484edea5930ac85c5ebf524d

included in BSP 2.8b4

The first issue is that currently the lvds-drive-strength property has been placed in the wrong device tree node, I’ve attached a patch that should fix the issue (it does for me).

The second issue is that NV_SOR_LANE4_DRIVE_CURRENT is still set fixed to 0x40, and this seems to cause artifacts if NV_SOR_LANE_DRIVE_CURRENT is set to a low current value (e.g. 0x04 = 1.6mA).

So with:

# grep DRIVE /sys/kernel/debug/tegra_sor/regs
NV_SOR_LANE_DRIVE_CURRENT(0)      04e  04040404
NV_SOR_LANE4_DRIVE_CURRENT(0)     050  00000004

I have no artifacts on the display, while with:

# grep DRIVE /sys/kernel/debug/tegra_sor/regs
NV_SOR_LANE_DRIVE_CURRENT(0)      04e  04040404
NV_SOR_LANE4_DRIVE_CURRENT(0)     050  00000040

I’m experiencing black horizontal lines on the display.

Please take a look at this issue.

Thanks,
Diego

2

Thank you for reporting the issue.
I’ve pushed a patch to our kernel git:
http://git1.toradex.com/cgit/linux-toradex.git/log/?h=toradex_tk1_l4t_r21.7-next