[PATCH v2 2/2] drm/rockchip: vop: fix irq disabled after vop driver probed

[Marc Zyngier]

Hi Heiko,

On 28/05/18 14:20, Heiko Stuebner wrote:
> From: Sandy Huang <hjc at 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 at rock-chips.com>
> [add commit message, moved to pm_runtime_get_if_in_use]
> Signed-off-by: Heiko Stuebner <heiko at 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.
> +	 */
> +	if (!pm_runtime_get_if_in_use(vop->dev))
> +		return IRQ_NONE;
> +
> +	if (WARN_ON(vop_core_clks_enable(vop)))

WARN_ON() in an interrupt handler can be quite dangerous. Could you tone
it down a bit, and at least make it only fire once? Something like a
pr_warn_once should be enough (the stack trace is not very relevant, and
seeing it once is enough to know that something is wrong).

> +		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:
> 

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...