Re: Improvements for the PS3

Hi Fredrik,

On Thu, Jul 19, 2018 at 10:14 PM Fredrik Noring [off-list ref] wrote:

quoted

quoted

quoted

so I added a sleep with

+     msleep(10000);

I can't see where you added the sleep, but 10s seems excessive.
If the real reason is the need to wait for an interrupt for ps3fb_sync_image(),
then waiting for 40 ms should be sufficient? Or am I missing something?

It's at the end of ps3fb_probe, as shown in the original post:

https://lists.ozlabs.org/pipermail/linuxppc-dev/2018-July/175771.html

Thanks, I had found that one in the mean time...

I thought 100 ms or so would work, but evidently it didn't. In fact, 1 s
for even 5 s didn't seem to work either. In any case, I would like to
develop a solution that does not need to sleep at all, so that will be my
first approach for a proper implementation.

Hmm...

quoted

quoted

I suppose the problem is that it relies on interrupts for ps3fb_sync_image

quoted

to regularly copy the image, hence without them the screen isn't updated to
show kernel panics, etc. Perhaps one way to fix that is to implement the
struct fb_tile_ops API, so that the console is synchronously updated? Would
that be acceptable?

I'm not sure if that would work or not.   Maybe Geert is more familiar with it.

That sounds like a complex solution, slowing down the console a lot.

Why would that be slow? I have implemented a similar technique for the
PlayStation 2 frame buffer, and (without any measurements at hand now) it
appears to be about as fast as is possible, and reasonably easy too. :)

[...]

OK, I retract my statement ;-)

quoted

What about letting ps3fb register a panic notifier to sync the screen, like
hyperv_fb does?

That would not work with kernel freezes unfortunately. Debugging those with
nondeterministicly invisible kernel prints would be painful, I believe.

Unfortunately AFAIK the PS3 doesn't have any other "synchronous" output we
can use for debugging (like flashing the power LED).

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds