Improvements for the PS3

[Geert Uytterhoeven]

Hi Geoff, Frederik,

On Thu, Jul 19, 2018 at 12:40 AM Geoff Levand <geoff at infradead.org> wrote:
> On 07/14/2018 09:49 AM, Fredrik Noring wrote:
> > 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?

> > +
> >       return 0;
> >
> > et voilà, the screen came alive and the kernel panic was revealed! It seems
> > the kernel panics so fast that the PS3 frame buffer is unprepared. This is,
> > of course, very unfortunate because trying to debug the boot process without
> > a screen or any other means of obtaining console text is quite difficult.
>
> We could add a fixed delay there, but I'd like to avoid waiting that
> long on every boot.  Why don't you add a kernel module_param named
> something like ps3fb_delay that takes a value in milliseconds and a
> default of zero.  See:
>
>   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/video/fbdev/ps3fb.c?h=v4.17#n260
>
> > I suppose the problem is that it relies on interrupts for ps3fb_sync_image
> > 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.

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

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at 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