Re: Proposal for a low-level Linux display framework

On Sat, Sep 17, 2011 at 11:11 AM, Florian Tobias Schandinat
[off-list ref] wrote:

On 09/17/2011 03:16 PM, Rob Clark wrote:

quoted

quoted

From userspace perspective, fbdev doesn't go away.  It is just a

legacy interface provided on top of DRM/KMS driver mostly via helper
functions.  With this approach, you get the richer KMS API (and all
the related plumbing for hotplug, EDID parsing, multi-head support,
flipping, etc) for userspace stuff that needs that, but can keep the
fbdev userspace interface for legacy apps.  It is the best of both
worlds.  There isn't really any good reason to propagate standalone
fbdev driver anymore.

I disagree. This depends on the functionality the hardware has, the desired
userspace and the manpower one has to do it. And of course if you just want fb
having fb via DRM/KMS has some overhead/bloat. It's perfectly okay to have just
an fb driver for devices that can't do more anyway.
And fb is no legacy interface but actively developed, just with other goals than
DRM/KMS is, it aims for stability and to provide a direct interface, not needing
any X or wayland crap.

Hmm, for simple enough devices, maybe fb is fine.. but if you are
covering a range of devices which include stuff with more
sophisticated userspace (X/wayland), then just doing DRM/KMS and using
the DRM fbdev helpers, vs doing both DRM/KMS and standalone fbdev..
well that seems like a no-brainer.

I still think, if you are starting a new driver, you should just go
ahead and use DRM/KMS.. a simple DRM/KMS driver that doesn't support
all the features is not so complex, and going this route future-proofs
you better when future generations of hardware gain more capabilities
and sw gain more requirements.

BR,
-R

Best regards,

Florian Tobias Schandinat
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