On 27/04/2020 14:15, Tomi Valkeinen wrote:
On 27/04/2020 14:10, Jyri Sarha wrote:
On 27/04/2020 13:51, Tomi Valkeinen wrote:
On 27/04/2020 13:37, Jyri Sarha wrote:
On 27/04/2020 13:09, Tero Kristo wrote:
+ status = "disabled";
Again, why disabled by default?
tidss device is not functional without a defined video-port. The driver
is not implemented in a way that it would handle a broken configuration
gracefully.
Then we need to fix it. The driver should handle the case where there
are no ports defined just fine.
Just by reading the code, I would say that currently the probe would
fail with returned -ENOMEM after calling drm_vblank_init() with zero CRTCs.
So should the probe fail gracefully and silently, or should we try to
register a DRM device with no CRTCs? Is that even possible?
My first thought is that the driver should exit probe silently with ENODEV if there are no outputs
defined (but, of course, with EPROBE_DEFER if there are outputs which haven't been probed yet).
It gets a bit more complex if we ever support writeback, as that can be used as mem-to-mem without
any displays, but I think we can ignore that for now.
In any case, that's not the reason for status = "disabled", so that discussion is not related to
these patches as such.
The reason to have DSS disabled is just to prevent pointless driver probing. When a board dts or a
DT overlay adds a display, the DSS DT node has to be modified anyway to add the DT graph and the
panel/bridge data. So one can as well add the single line of "status = enabled" there.
Tomi
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