On 28/05/18 14:20, Heiko Stuebner wrote:

From: Sandy Huang hjc@rock-chips.com

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@rock-chips.com [add commit message, moved to pm_runtime_get_if_in_use] Signed-off-by: Heiko Stuebner heiko@sntech.de

---

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.

Robin.

• */
  

• 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:

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@rock-chips.com

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@rock-chips.com [add commit message, moved to pm_runtime_get_if_in_use] Signed-off-by: Heiko Stuebner heiko@sntech.de

---

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: