[Letux-kernel] Pyra display driver once again broken in v5.2-rc1

H. Nikolaus Schaller hns at goldelico.com
Mon May 27 21:25:41 CEST 2019

> Am 27.05.2019 um 14:46 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> Hi,
> unfortunately every year or so some upstream change breaks
> our (still out-of tree) DSI panel driver for the Pyra(Phone).
> This time it happened with v5.2-rc1.
> v5.2-rc1 also broke the GTA04 display and the L3704/L7004 displays,
> but those are DPI panels and the reasons were two separate
> issues which have nothing to do with the Pyra DSI panel.
> There have been some API changes for DSI panel drivers and
> I have done a
> 	git diff v5.2-rc1 v5.1 drivers/gpu/drm/omapdrm/displays/panel-dsi-cm.c
> to identify them and tried to apply similar patches to our
> panel. But still the driver is successfully probed, but shows
> not activity. No calls to enable() or connect(). Backlight stays
> black. And as a result there is also no /dev/fb0, text console
> or X11.
> Unfortunately, it has not improved after upgrading to v5.2-rc2.
> So once again it appears that I have to git bisect upstream
> patches to find out what is going on...

After spending more hours... it does not seem to be in our patches
and the panel driver is likely almost correct now.

I believe this because I also found not working:
* dwc3 (usb3/otg port)
* bq24297 battery charger driver (my Pyra fortunately runs well enough with U-Boot initialization)
* tca6424 (gpio expander - we use the pcal9524 variant)

The tca6424 driver seems to be broken (not loaded).

And since it is used for interrupt detection of the bq24297, the charger
driver defers probing.

Because the charger driver does not load, there is no otg booster to
successfully probe dwc3.

So this looks like a clear failure chain.

Additionally, the tca6424 is used for the HDMI port and maybe
a missing tca6424 is sufficient to stop omapdss initialization
although probed.

So far this analysis.

Help (at least discussion) is really welcome because I don't know
how much voluntary time I can and want to invest into such bugs.

BR and thanks,

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