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drm/msm/sde: fix race condition in vblank control interrupts

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In Dual display concurrencies there are certain cases where
irq_idx and vblank_refcount state mismatch can occur.
To avoid it, during setup of irq_hw_idx, reset the vblank_refcount
and unregister read ptr irq if not yet done by then along with
maintaining global mutex lock for vblank_refcount.
Also, if register IRQ fails, correct vblank_refcount so
that IRQ registration can be tried again.

Change-Id: I06bcbf71c6a43bd161ff61093d9f6063a292d6bc
Signed-off-by: Raviteja Tamatam <travitej@codeaurora.org>
Signed-off-by: Samantha Tran <samtran@codeaurora.org>
This commit is contained in:
Samantha Tran
2020-01-16 12:06:34 -08:00
committed by Gerrit - the friendly Code Review server
parent 83ff89732a
commit 0064a0227b
3 changed files with 34 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

35
msm/sde/sde_encoder_phys_cmd.c
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@@ -320,6 +320,8 @@ static void _sde_encoder_phys_cmd_setup_irq_hw_idx(
struct sde_encoder_phys *phys_enc)
{
struct sde_encoder_irq *irq;
struct sde_kms *sde_kms = phys_enc->sde_kms;
int ret = 0;
if (!phys_enc || !phys_enc->hw_pp || !phys_enc->hw_ctl) {
SDE_ERROR("invalid args %d %d\n", !phys_enc,
@@ -332,6 +334,21 @@ static void _sde_encoder_phys_cmd_setup_irq_hw_idx(
return;
}
mutex_lock(&sde_kms->vblank_ctl_global_lock);
if (atomic_read(&phys_enc->vblank_refcount)) {
SDE_ERROR(
"vblank_refcount mismatch detected, try to reset %d\n",
atomic_read(&phys_enc->vblank_refcount));
ret = sde_encoder_helper_unregister_irq(phys_enc,
INTR_IDX_RDPTR);
if (ret)
SDE_ERROR(
"control vblank irq registration error %d\n",
ret);
}
atomic_set(&phys_enc->vblank_refcount, 0);
irq = &phys_enc->irq[INTR_IDX_CTL_START];
irq->hw_idx = phys_enc->hw_ctl->idx;
irq->irq_idx = -EINVAL;
@@ -365,6 +382,8 @@ static void _sde_encoder_phys_cmd_setup_irq_hw_idx(
else
irq->hw_idx = phys_enc->hw_pp->idx;
mutex_unlock(&sde_kms->vblank_ctl_global_lock);
}
static void sde_encoder_phys_cmd_cont_splash_mode_set(
@@ -800,13 +819,15 @@ static int sde_encoder_phys_cmd_control_vblank_irq(
to_sde_encoder_phys_cmd(phys_enc);
int ret = 0;
int refcount;
struct sde_kms *sde_kms;
if (!phys_enc || !phys_enc->hw_pp) {
SDE_ERROR("invalid encoder\n");
return -EINVAL;
}
sde_kms = phys_enc->sde_kms;
mutex_lock(phys_enc->vblank_ctl_lock);
mutex_lock(&sde_kms->vblank_ctl_global_lock);
refcount = atomic_read(&phys_enc->vblank_refcount);
/* Slave encoders don't report vblank */
@@ -824,11 +845,17 @@ static int sde_encoder_phys_cmd_control_vblank_irq(
SDE_EVT32(DRMID(phys_enc->parent), phys_enc->hw_pp->idx - PINGPONG_0,
enable, refcount);
if (enable && atomic_inc_return(&phys_enc->vblank_refcount) == 1)
if (enable && atomic_inc_return(&phys_enc->vblank_refcount) == 1) {
ret = sde_encoder_helper_register_irq(phys_enc, INTR_IDX_RDPTR);
else if (!enable && atomic_dec_return(&phys_enc->vblank_refcount) == 0)
if (ret)
atomic_dec_return(&phys_enc->vblank_refcount);
} else if (!enable &&
atomic_dec_return(&phys_enc->vblank_refcount) == 0) {
ret = sde_encoder_helper_unregister_irq(phys_enc,
INTR_IDX_RDPTR);
if (ret)
atomic_inc_return(&phys_enc->vblank_refcount);
}
end:
if (ret) {
@@ -840,7 +867,7 @@ end:
enable, refcount, SDE_EVTLOG_ERROR);
}
mutex_unlock(phys_enc->vblank_ctl_lock);
mutex_unlock(&sde_kms->vblank_ctl_global_lock);
return ret;
}