[Letux-kernel] [PATCH 00/20] A bunch of JZ4730 fixups for letux-kernel

H. Nikolaus Schaller hns at goldelico.com
Tue Jan 12 15:54:55 CET 2021

> Am 12.01.2021 um 15:17 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> I could pinpoint this to drm_mode_legacy_fb_format()
> https://elixir.bootlin.com/linux/v5.11-rc3/source/drivers/gpu/drm/drm_fourcc.c#L46
> There is no case for bpp=32 and depth=16.
> I just want to try to add a case 16: fmt = DRM_FORMAT_RGB565; and let's see...

Yes, that makes it work - except the vblank timeouts which we know have a different reason.

BTW: CGU_REG_CFCR2 and CFCR.PFR still differ from 2.6.24-Kernel.

0x10000000 0d523220 CGU_REG_CFCR
0x10000060 0000000b CGU_REG_CFCR2

0x10000000 0d522220 CGU_REG_CFCR
0x10000060 0000000c CGU_REG_CFCR2

I.e. LFR=3 vs. LFR=2 - so we may have the LCD clock running at 50% higher speed (maybe exceeding the 150 MHz limit?)
And PXFR=11 vs. PXFR=12 - this is a small deviation of less than 10%.

But before looking at this I now want to find out why the DMA descriptors are not properly set up...

And why there are no vblank interrupts. Maybe this are just two symptoms of the same reason.


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