On 29/05/18 13:17, Heiko Stübner wrote:
Am Dienstag, 29. Mai 2018, 13:59:42 CEST schrieb Robin Murphy:
On 28/05/18 14:20, Heiko Stuebner wrote:
From: Sandy Huang <hjc@xxxxxxxxxxxxxx>
The vop irq is shared between vop and iommu and irq probing in the
iommu driver moved to the probe function recently. This can in some
cases lead to a stall if the irq is triggered while the vop driver
still has it disabled, but the vop irq handler gets called.
But there is no real need to disable the irq, as the vop can simply
also track its enabled state and ignore irqs in that case.
For this we can simply check the power-domain state of the vop,
similar to how the iommu driver does it.
So remove the enable/disable handling and add appropriate condition
to the irq handler.
changes in v2:
- move to just check the power-domain state
- add clock handling
Signed-off-by: Sandy Huang <hjc@xxxxxxxxxxxxxx>
[add commit message, moved to pm_runtime_get_if_in_use]
Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx>
---
drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 28 ++++++++++++++-------
1 file changed, 19 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c index
b55156b8ba3b..615a5b44bfe9 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -573,8 +573,6 @@ static int vop_enable(struct drm_crtc *crtc)
spin_unlock(&vop->reg_lock);
- enable_irq(vop->irq);
-
drm_crtc_vblank_on(crtc);
return 0;
@@ -618,8 +616,6 @@ static void vop_crtc_atomic_disable(struct drm_crtc
*crtc,>
vop_dsp_hold_valid_irq_disable(vop);
- disable_irq(vop->irq);
-
vop->is_enabled = false;
/*
@@ -1195,6 +1191,16 @@ static irqreturn_t vop_isr(int irq, void *data)
uint32_t active_irqs;
int ret = IRQ_NONE;
+ /*
+ * The irq is shared with the iommu. If the power-domain is off
+ * the irq has to be targetted at the iommu.
Hmm, aren't the IOMMUs in the same power domain as their respective
master, though? I would naively assume so, and it does look that way
from the DTs in the BSP kernel.
AFAICS the IOMMU usage count should never be greater than the VOP usage
count (except before the VOP driver has probed, but I don't think that
matters), so although this looks like a sensible change in general I
can't help be a little bit puzzled at how and why the flow works.
Ok, the comment might be misleading. It actually means to use the runtime-pm
state of the vop-_device_ as a check.
I.e. in vop_initials(), Marc added the patch clearing and masking all vop
interrupts. In vop_enable() we have runtime_get_... + enablement of
vop interrupts, which get disabled in vop_disable again.
That way, checking the runtime_pm state should be an indicator if the
irq is for the vop and not the iommu.
Right, but whenever the VOP is nominally-disabled, the IOMMU should also
be nominally-disabled, in which case if it's even possible for the IRQ
to be asserted, both drivers would ignore it for the same reason (plus
the IOMMU driver would also spew a WARN(), which I'm not sure is always
appropriate...). That's what I couldn't quite make sense of.
However, from serendipitously stumbling across [1] I see that the IOMMU
is in fact going to get explicitly enabled by the driver core around
probing the VOP, which does give a window during which the imbalance is
present. I can imagine that the IOMMU reset via the VOP driver's
dma_configure_call() might misbehave if e.g. the VOP was left running
from a bootloader splash screen, but in that case I would expect to see
various screaming from the IOMMU driver which wasn't apparent in
Ezequiel's log. Oh well, as I said before the patch looks sane
regardless of my ability to reason about it ;)
Robin.
[1] https://patchwork.kernel.org/patch/10408825/
+ */
+ if (!pm_runtime_get_if_in_use(vop->dev))
+ return IRQ_NONE;
+
+ if (WARN_ON(vop_core_clks_enable(vop)))
+ goto out;
+
/*
* interrupt register has interrupt status, enable and clear bits, we
* must hold irq_lock to avoid a race with enable/disable_vblank().
@@ -1209,8 +1215,11 @@ static irqreturn_t vop_isr(int irq, void *data)
spin_unlock(&vop->irq_lock);
/* This is expected for vop iommu irqs, since the irq is shared */
- if (!active_irqs)
- return IRQ_NONE;
+ if (!active_irqs) {
+ ret = IRQ_NONE;
+ vop_core_clks_disable(vop);
+ goto out;
+ }
if (active_irqs & DSP_HOLD_VALID_INTR) {
complete(&vop->dsp_hold_completion);
@@ -1236,6 +1245,10 @@ static irqreturn_t vop_isr(int irq, void *data)
DRM_DEV_ERROR(vop->dev, "Unknown VOP IRQs: %#02x\n",
active_irqs);
+ vop_core_clks_disable(vop);
+
+out:
+ pm_runtime_put(vop->dev);
return ret;
}
@@ -1614,9 +1627,6 @@ static int vop_bind(struct device *dev, struct
device *master, void *data)>
if (ret)
goto err_disable_pm_runtime;
- /* IRQ is initially disabled; it gets enabled in power_on */
- disable_irq(vop->irq);
-
return 0;
err_disable_pm_runtime:
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