On 18.12.2017 12:28, Marc Zyngier wrote: > Stopping the X display manager on a kevin platform results in the > following crash: > > [ 674.833536] Synchronous External Abort: synchronous external abort (0x96000010) at 0xffff00000c970640 > [ 674.843886] Internal error: : 96000010 [#1] PREEMPT SMP > [ 674.849744] Modules linked in: > [ 674.849755] CPU: 1 PID: 86 Comm: kworker/1:1 Not tainted 4.15.0-rc3-00057-gff24f8cf492d-dirty #3 > [ 674.849760] detected fb_set_par error, error code: -16 > [ 674.849761] Hardware name: Google Kevin (DT) > [ 674.849773] Workqueue: events analogix_dp_psr_work > [ 674.849778] pstate: 60000005 (nZCv daif -PAN -UAO) > [ 674.849784] pc : analogix_dp_send_psr_spd+0x8/0x168 > [ 674.849788] lr : analogix_dp_enable_psr+0x54/0x60 > [ 674.849789] sp : ffff000009b2bd60 > [ 674.849790] x29: ffff000009b2bd60 x28: 0000000000000000 > [ 674.849794] x27: ffff000009913d20 x26: ffff00000900fbf0 > [ 674.849797] x25: ffff8000f1b30000 x24: ffff8000f0c21d98 > [ 674.849800] x23: 0000000000000000 x22: ffff8000f7d3aa00 > [ 674.849803] x21: ffff8000f7d36980 x20: ffff8000f0c21c18 > [ 674.849806] x19: ffff8000f0c21db8 x18: 0000000000000001 > [ 674.849809] x17: 0000ffff89f2ed58 x16: ffff000008222908 > [ 674.849812] x15: 0000000000000000 x14: 0000000000000400 > [ 674.849815] x13: 0000000000000400 x12: 0000000000000000 > [ 674.849817] x11: 0000000000001414 x10: 0000000000000a00 > [ 674.849820] x9 : ffff000009b2bbb0 x8 : ffff8000f1b30a60 > [ 674.849823] x7 : 0000000000080000 x6 : 0000000000000001 > [ 674.849826] x5 : 0000000000000010 x4 : 0000000000000007 > [ 674.849829] x3 : 0000000000000002 x2 : ffff00000c970640 > [ 674.849832] x1 : ffff000009b2bd78 x0 : ffff8000f1624018 > [ 674.849836] Process kworker/1:1 (pid: 86, stack limit = 0x0000000083e5f7c3) > [ 674.849838] Call trace: > [ 674.849842] analogix_dp_send_psr_spd+0x8/0x168 > [ 674.849844] analogix_dp_psr_work+0x9c/0xa0 > [ 674.849849] process_one_work+0x1cc/0x328 > [ 674.849852] worker_thread+0x50/0x450 > [ 674.849856] kthread+0xf8/0x128 > [ 674.849860] ret_from_fork+0x10/0x18 > [ 674.849864] Code: b9000001 d65f03c0 f9445802 91190042 (b9400042) > > Further investigation show that this happens because the the workqueue > races with the analogix_dp_bridge_disable() call from the core DRM code, > and end up trying to write to the DP bridge that has already been powered > down. This result is a very black screen, and a hard reset. > > Instead of counting on luck to keep the bridge alive, let's use the > pm_runtime framework and take a reference on the device when we're about > to poke it. That is a fairly big hammer, but one that allows the system > to stay alive across dozens of X start/stop sequences. Wouldn't be better to cancel the work in analogix_dp_bridge_disable, it looks safer. Regards Andrzej > > Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> > --- > drivers/gpu/drm/rockchip/analogix_dp-rockchip.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c > index 08743ad96cb9..7f2c190f75e7 100644 > --- a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c > +++ b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c > @@ -14,6 +14,7 @@ > > #include <linux/component.h> > #include <linux/mfd/syscon.h> > +#include <linux/pm_runtime.h> > #include <linux/of_device.h> > #include <linux/of_graph.h> > #include <linux/regmap.h> > @@ -113,10 +114,12 @@ static void analogix_dp_psr_work(struct work_struct *work) > } > > mutex_lock(&dp->psr_lock); > + pm_runtime_get_sync(dp->dev); > if (dp->psr_state == EDP_VSC_PSR_STATE_ACTIVE) > analogix_dp_enable_psr(dp->dev); > else > analogix_dp_disable_psr(dp->dev); > + pm_runtime_put_sync(dp->dev); > mutex_unlock(&dp->psr_lock); > } > > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
