Re: [RFC][PATCH] drm: kirin: Add a mutex to avoid fb initialization race

[liuxinliang]

On 2017/2/25 5:33, John Stultz wrote:
> On Thu, Feb 23, 2017 at 5:55 PM, liuxinliang
> <z.liuxinliang@xxxxxxxxxxxxx> wrote:
> > Hi John,
> >
> > On 2017/2/23 8:56, John Stultz wrote:
> > > In some cases I've been seeing a race where two framebuffers
> > > would be initialized, as kirin_fbdev_output_poll_changed()
> > > might get called quickly in succession, resulting in the fb
> > > initialization happening twice. This could cause the system
> >
> > I might understand this race. This because two places call
> > drm_helper_hpd_irq_event might cause the race:
> > One place is here
> > static int kirin_drm_kms_init(struct drm_device *dev)
> > {
> > ...
> >      /* force detection after connectors init */
> >      (void)drm_helper_hpd_irq_event(dev);
> > ...
> > }
> >
> > another is the adv7533 interrupt thread handler
> > static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd)
> > {
> > ...
> >      if (process_hpd && irq0 & ADV7511_INT0_HPD && adv7511->bridge.encoder)
> >          drm_helper_hpd_irq_event(adv7511->connector.dev);
> > ...
> > }
> >
> > right?
> >
> > I don't get a better way to fix this yet , I like to put fb_lock into
> > kirin_drm_private.
> Ok. I've moved the mutex to the kirin_drm_private structure.
>
> Anything else you'd like to see before I resend?

Thanks, no more then.


Best,
-xinliang

> thanks
> -john
>
> .