linux-kernel - [PATCH v2 5/5] iommu/mediatek: Always tlb_flush

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Date:   Wed,  8 Dec 2021 14:07:44 +0200
From:   Dafna Hirschfeld <dafna.hirschfeld@...labora.com>
To:     iommu@...ts.linux-foundation.org, Yong Wu <yong.wu@...iatek.com>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-mediatek@...ts.infradead.org (moderated list:MEDIATEK IOMMU
        DRIVER),
        linux-arm-kernel@...ts.infradead.org (moderated list:ARM/Mediatek SoC
        support), linux-kernel@...r.kernel.org (open list),
        dafna.hirschfeld@...labora.com, kernel@...labora.com,
        linux-media@...r.kernel.org, sebastian.reichel@...labora.com
Subject: [PATCH v2 5/5] iommu/mediatek: Always tlb_flush_all when each PM resume

From: Yong Wu <yong.wu@...iatek.com>

Prepare for 2 HWs that sharing pgtable in different power-domains.

When there are 2 M4U HWs, it may has problem in the flush_range in which
we get the pm_status via the m4u dev, BUT that function don't reflect the
real power-domain status of the HW since there may be other HW also use
that power-domain.

DAM allocation is often done while the allocating device is runtime
suspended. In such a case the iommu will also be suspended and partial
flushing of the tlb will not be executed.
Therefore, we add a tlb_flush_all in the pm_runtime_resume to make
sure the tlb is always clean.

In other case, the iommu's power should be active via device
link with smi.

Signed-off-by: Yong Wu <yong.wu@...iatek.com>
[move the call to mtk_iommu_tlb_flush_all to the bottom of resume cb, improve doc/log]
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@...labora.com>
---
 drivers/iommu/mtk_iommu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 195a411e3087..4799cd06511b 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -997,6 +997,13 @@ static int __maybe_unused mtk_iommu_runtime_resume(struct device *dev)
 	writel_relaxed(reg->ivrp_paddr, base + REG_MMU_IVRP_PADDR);
 	writel_relaxed(reg->vld_pa_rng, base + REG_MMU_VLD_PA_RNG);
 	writel(m4u_dom->cfg.arm_v7s_cfg.ttbr & MMU_PT_ADDR_MASK, base + REG_MMU_PT_BASE_ADDR);
+
+	/*
+	 * Users may allocate dma buffer before they call pm_runtime_get,
+	 * in which case it will lack the necessary tlb flush.
+	 * Thus, make sure to update the tlb after each PM resume.
+	 */
+	mtk_iommu_tlb_flush_all(data);
 	return 0;
 }
 
-- 
2.17.1