Re: [PATCH] drm/rockchip: analogix_dp: Use mutex rather than spinlock

[Mark yao]

On 2017å11æ10æ 20:07, Enric Balletbo Serra wrote:
> 2017-10-04 19:53 GMT+02:00 Emil Renner Berthing <kernel@xxxxxxxx>:
> > On the Samsung Chromebook Plus I get this error with 4.14-rc3:
> >
> > BUG: scheduling while atomic: kworker/3:1/50/0x00000002
> > Modules linked in:
> > CPU: 3 PID: 50 Comm: kworker/3:1 Not tainted 4.14.0-0.rc3-kevin #2
> > Hardware name: Google Kevin (DT)
> > Workqueue: events analogix_dp_psr_work
> > Call trace:
> > [<ffffff80080873b0>] dump_backtrace+0x0/0x320
> > [<ffffff80080876e4>] show_stack+0x14/0x20
> > [<ffffff8008606d38>] dump_stack+0x9c/0xbc
> > [<ffffff80080c6b5c>] __schedule_bug+0x4c/0x70
> > [<ffffff80086188c0>] __schedule+0x3f0/0x458
> > [<ffffff8008618960>] schedule+0x38/0xa0
> > [<ffffff800861c20c>] schedule_hrtimeout_range_clock+0x84/0xe8
> > [<ffffff800861c2a0>] schedule_hrtimeout_range+0x10/0x18
> > [<ffffff800861bcec>] usleep_range+0x64/0x78
> > [<ffffff8008415a6c>] analogix_dp_transfer+0x16c/0x340
> > [<ffffff8008412550>] analogix_dpaux_transfer+0x10/0x18
> > [<ffffff80083ceb14>] drm_dp_dpcd_access+0x4c/0xf0
> > [<ffffff80083cf614>] drm_dp_dpcd_write+0x1c/0x28
> > [<ffffff8008413b98>] analogix_dp_disable_psr+0x60/0xa8
> > [<ffffff800840da3c>] analogix_dp_psr_work+0x4c/0x90
> > [<ffffff80080bb09c>] process_one_work+0x1d4/0x348
> > [<ffffff80080bb258>] worker_thread+0x48/0x478
> > [<ffffff80080c11fc>] kthread+0x12c/0x130
> > [<ffffff8008084290>] ret_from_fork+0x10/0x18
> >
> > Changing rockchip_dp_device::psr_lock to a mutex rather
> > than spinlock seems to fix the issue.
> >
> > Signed-off-by: Emil Renner Berthing <kernel@xxxxxxxx>
> > ---
> >   drivers/gpu/drm/rockchip/analogix_dp-rockchip.c | 14 ++++++--------
> >   1 file changed, 6 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
> > index 9606121fa185..d8f72d87ef08 100644
> > --- a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
> > +++ b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
> > @@ -72,7 +72,7 @@ struct rockchip_dp_device {
> >          struct reset_control     *rst;
> >
> >          struct work_struct       psr_work;
> > -       spinlock_t               psr_lock;
> > +       struct mutex             psr_lock;
> >          unsigned int             psr_state;
> >
> >          const struct rockchip_dp_chip_data *data;
> > @@ -83,21 +83,20 @@ struct rockchip_dp_device {
> >   static void analogix_dp_psr_set(struct drm_encoder *encoder, bool enabled)
> >   {
> >          struct rockchip_dp_device *dp = to_dp(encoder);
> > -       unsigned long flags;
> >
> >          if (!analogix_dp_psr_supported(dp->dev))
> >                  return;
> >
> >          dev_dbg(dp->dev, "%s PSR...\n", enabled ? "Entry" : "Exit");
> >
> > -       spin_lock_irqsave(&dp->psr_lock, flags);
> > +       mutex_lock(&dp->psr_lock);
> >          if (enabled)
> >                  dp->psr_state = EDP_VSC_PSR_STATE_ACTIVE;
> >          else
> >                  dp->psr_state = ~EDP_VSC_PSR_STATE_ACTIVE;
> >
> >          schedule_work(&dp->psr_work);
> > -       spin_unlock_irqrestore(&dp->psr_lock, flags);
> > +       mutex_unlock(&dp->psr_lock);
> >   }
> >
> >   static void analogix_dp_psr_work(struct work_struct *work)
> > @@ -105,7 +104,6 @@ static void analogix_dp_psr_work(struct work_struct *work)
> >          struct rockchip_dp_device *dp =
> >                                  container_of(work, typeof(*dp), psr_work);
> >          int ret;
> > -       unsigned long flags;
> >
> >          ret = rockchip_drm_wait_vact_end(dp->encoder.crtc,
> >                                           PSR_WAIT_LINE_FLAG_TIMEOUT_MS);
> > @@ -114,12 +112,12 @@ static void analogix_dp_psr_work(struct work_struct *work)
> >                  return;
> >          }
> >
> > -       spin_lock_irqsave(&dp->psr_lock, flags);
> > +       mutex_lock(&dp->psr_lock);
> >          if (dp->psr_state == EDP_VSC_PSR_STATE_ACTIVE)
> >                  analogix_dp_enable_psr(dp->dev);
> >          else
> >                  analogix_dp_disable_psr(dp->dev);
> > -       spin_unlock_irqrestore(&dp->psr_lock, flags);
> > +       mutex_unlock(&dp->psr_lock);
> >   }
> >
> >   static int rockchip_dp_pre_init(struct rockchip_dp_device *dp)
> > @@ -381,7 +379,7 @@ static int rockchip_dp_bind(struct device *dev, struct device *master,
> >          dp->plat_data.power_off = rockchip_dp_powerdown;
> >          dp->plat_data.get_modes = rockchip_dp_get_modes;
> >
> > -       spin_lock_init(&dp->psr_lock);
> > +       mutex_init(&dp->psr_lock);
> >          dp->psr_state = ~EDP_VSC_PSR_STATE_ACTIVE;
> >          INIT_WORK(&dp->psr_work, analogix_dp_psr_work);
> >
> > --
> > 2.14.2
> Right this patch fixes the issue for me too.
>
> Tested-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
Right, it's a bug using spinlock with sleep,

Pushed to drm-misc-fixes

Thanks.

--
ïark Yao