Hi Heiko,
On 12/06/18 13:15, 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
> changes in v3:
> - clarify comment to speak of runtime-pm not power-domain
>
> Fixes: d0b912bd4c23 ("iommu/rockchip: Request irqs in rk_iommu_probe()")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Sandy Huang <hjc@xxxxxxxxxxxxxx>
> Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx>
> Tested-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> ---
> 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 9a1f272e41c7..ae8a69793aed 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 runtime-pm state of the
> + * vop-device is disabled 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)))
> + goto out;
As I mentioned before, a WARN_ON() in an interrupt handler is a good way
to make a bad problem even worse, and will give information (full
register and stack dump) that is mostly useless to the context at hand.
Turning it to a dev_warn_ratelimited() (or DRM_ERROR_RATELIMITED if you
want to be DRM compliant) would be a better approach, IMHO.
> +
> /*
> * 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;
> + }
A couple of nits: ret is already set to IRQ_NONE at this stage, and you
could simply rewrite it as:
if (!active_irq)
goto out_disable;
>
> 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);
>
with the "out_disable" label placed here.
> + 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...
