[PATCH] drm: hdlcd: allow HDLCD to be used without interrupt

On Wed, Aug 30, 2017 at 11:54:14AM +0100, Liviu Dudau wrote:

On Tue, Aug 29, 2017 at 05:48:24PM +0100, Russell King - ARM Linux wrote:

quoted

On Tue, Aug 29, 2017 at 02:33:52PM +0100, Liviu Dudau wrote:

quoted

I've worked with Vladimir Murzin inside ARM to try to sort out problems
on the board like the one that you have. He's got to a point where the HDLCD
starts correctly after adding a non-fixed pxlclk source, but then the rest of
the setup is semi-useless without a working IRQ because DRM atomic calls
will give you a vblank timeout splat everytime you invoke them. So I'm
not sure how you want to progress with this patch, as not having an IRQ
line means you will not get any vblank interrupts and you can't use the
driver with userspace that calls DRM API.

The RTL guys are apparently working on a fix, but I have no ETA or
details on when they are going to do.

It sounds then like this patch doesn't make sense - so I'm happy
for it to be dropped.  It's something to bear in mind in the future
when folk decide whether to adopt fbdev or DRM support for hardware
that gets used in MMU-less hardware...

I don't think this has anything to do with the presence of a MMU or not.

It doesn't directly, but nommu is probably more likely to not wire the
interrupt than mmu systems, on the grounds that nommu is more embedded.

-- 
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