linux-kernel - Re: [PATCH 2/2] iommu/rockchip: Move irq request past pm_runtime

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Date:   Tue, 07 Aug 2018 13:45:26 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Joerg Roedel <joro@...tes.org>,
        Jeffy Chen <jeffy.chen@...k-chips.com>
Subject: Re: [PATCH 2/2] iommu/rockchip: Move irq request past pm_runtime_enable

Am Dienstag, 7. August 2018, 10:54:06 CEST schrieb Marc Zyngier:
> Enabling the interrupt early, before power has been applied to the
> device, can result in an interrupt being delivered too early if:
> 
> - the IOMMU shares an interrupt with a VOP
> - the VOP has a pending interrupt (after a kexec, for example)
> 
> In these conditions, we end-up taking the interrupt without
> the IOMMU being ready to handle the interrupt (not powered on).
> 
> Moving the interrupt request past the pm_runtime_enable() call
> makes sure we can at least access the IOMMU registers. Note that
> this is only a partial fix, and that the VOP interrupt will still
> be screaming until the VOP driver kicks in, which advocates for
> a more synchronized interrupt enabling/disabling approach.
> 
> Fixes: 0f181d3cf7d98 ("iommu/rockchip: Add runtime PM support")
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>

Reviewed-by: Heiko Stuebner <heiko@...ech.de>