Hi
Am 20.02.25 um 10:18 schrieb Tomi Valkeinen:
[...]
+ * Color modes of 10, 12, 15, 30 and 64 are only supported for use by
+ * legacy user space. Please don't use them in new code. Other modes
+ * are not support.
+ *
+ * Do not attempt to allocate anything but linear framebuffer memory
+ * with single-plane RGB data. Allocation of other framebuffer
+ * layouts requires dedicated ioctls in the respective DRM driver.
According to this, every driver that supports, say, NV12, should
implement their own custom ioctl to do the exact same thing? And, of
course, every userspace app that uses, say, NV12, should then add code
for all these platforms to call the custom ioctls?
Yes, that's exactly the current status.
There has been discussion about a new dumb-create ioctl that takes a DRM
format as parameter. I'm all for it, but it's out of the scope for this
series.
As libdrm's modetest currently supports YUV formats with dumb buffers,
should we remove that code, as it's not correct and I'm sure people
use libdrm code as a reference?
Of course not.
Well, I'm not serious above, but I think all my points from the
earlier version are still valid. I don't like this. It changes the
parameters of the ioctl (bpp used to be bits-per-pixel, not it's
"color mode"), and the behavior of the ioctl, behavior that we've had
for a very long time, and we have no idea how many users there are
that will break (could be none, of course). And the documentation
changes make the current behavior and uses wrong or legacy.
Before I go into details about this statement, what use case exactly are
you referring to when you say that behavior changes?
Best regards
Thomas
Clearly we need something new and better for the buffer allocation,
but for the time being, I'd be more comfortable just keep the current
behavior, at least for all the drivers I use or maintain: omapdrm,
tidss, renesas, xlnx, tilcdc.
Tomi
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
