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References: <20210119105203.15530-1-yong.wu@mediatek.com>
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From:   Rob Herring <robh+dt@kernel.org>
Date:   Wed, 27 Jan 2021 13:07:01 -0600
Message-ID: <CAL_JsqJB=MMeMobznBiAUihJLBt5aeiiL+AtDWh6tajePu=Now@mail.gmail.com>
Subject: Re: [PATCH v2] of/device: Update dma_range_map only when dev has
 valid dma-ranges
To:     Yong Wu <yong.wu@mediatek.com>
Cc:     Joerg Roedel <joro@8bytes.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Paul Kocialkowski <paul.kocialkowski@bootlin.com>,
        Tomasz Figa <tfiga@google.com>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        srv_heupstream <srv_heupstream@mediatek.com>,
        devicetree@vger.kernel.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Linux IOMMU <iommu@lists.linux-foundation.org>,
        Nicolas Boichat <drinkcat@chromium.org>,
        Frank Rowand <frowand.list@gmail.com>
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Precedence: bulk

On Tue, Jan 19, 2021 at 4:52 AM Yong Wu <yong.wu@mediatek.com> wrote:
>
> The commit e0d072782c73 ("dma-mapping: introduce DMA range map,
> supplanting dma_pfn_offset") always update dma_range_map even though it was
> already set, like in the sunxi_mbus driver. the issue is reported at [1].
> This patch avoid this(Updating it only when dev has valid dma-ranges).

only when dev *doesn't* have valid dma-ranges?

> Meanwhile, dma_range_map contains the devices' dma_ranges information,
> This patch moves dma_range_map before of_iommu_configure. The iommu
> driver may need to know the dma_address requirements of its iommu
> consumer devices.
>
> [1] https://lore.kernel.org/linux-arm-kernel/5c7946f3-b56e-da00-a750-be097c7ceb32@arm.com/
>
> CC: Rob Herring <robh+dt@kernel.org>
> CC: Frank Rowand <frowand.list@gmail.com>
> Fixes: e0d072782c73 ("dma-mapping: introduce DMA range map, supplanting dma_pfn_offset"),
> Suggested-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> Reviewed-by: Rob Herring <robh@kernel.org>
> ---
>  drivers/of/device.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index aedfaaafd3e7..1122daa8e273 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -162,9 +162,11 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
>         mask = DMA_BIT_MASK(ilog2(end) + 1);
>         dev->coherent_dma_mask &= mask;
>         *dev->dma_mask &= mask;
> -       /* ...but only set bus limit if we found valid dma-ranges earlier */
> -       if (!ret)
> +       /* ...but only set bus limit and range map if we found valid dma-ranges earlier */
> +       if (!ret) {
>                 dev->bus_dma_limit = end;
> +               dev->dma_range_map = map;
> +       }
>
>         coherent = of_dma_is_coherent(np);
>         dev_dbg(dev, "device is%sdma coherent\n",
> @@ -172,6 +174,9 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
>
>         iommu = of_iommu_configure(dev, np, id);
>         if (PTR_ERR(iommu) == -EPROBE_DEFER) {
> +               /* Don't touch range map if it wasn't set from a valid dma-ranges */
> +               if (!ret)
> +                       dev->dma_range_map = NULL;
>                 kfree(map);
>                 return -EPROBE_DEFER;
>         }
> @@ -181,7 +186,6 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
>
>         arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);
>
> -       dev->dma_range_map = map;
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(of_dma_configure_id);
> --
> 2.18.0
>