linux-kernel - Re: [PATCH AUTOSEL 5.4 11/14] drm/msm: Stop using iommu

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Date:   Tue, 19 Apr 2022 11:53:23 -0700
From:   Rob Clark <robdclark@...omium.org>
To:     Sasha Levin <sashal@...nel.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Robin Murphy <robin.murphy@....com>,
        Rob Clark <robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        sean@...rly.run, airlied@...ux.ie, daniel@...ll.ch,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org
Subject: Re: [PATCH AUTOSEL 5.4 11/14] drm/msm: Stop using iommu_present()

You might want to drop this one, it seems to be causing some issues on
older generations.. I'll be sending another PR shortly with a revert.

https://patchwork.freedesktop.org/patch/482453

BR,
-R

On Tue, Apr 19, 2022 at 11:15 AM Sasha Levin <sashal@...nel.org> wrote:
>
> From: Robin Murphy <robin.murphy@....com>
>
> [ Upstream commit e2a88eabb02410267519b838fb9b79f5206769be ]
>
> Even if some IOMMU has registered itself on the platform "bus", that
> doesn't necessarily mean it provides translation for the device we
> care about. Replace iommu_present() with a more appropriate check.
>
> Signed-off-by: Robin Murphy <robin.murphy@....com>
> Reviewed-by: Rob Clark <robdclark@...il.com>
> Patchwork: https://patchwork.freedesktop.org/patch/480707/
> Link: https://lore.kernel.org/r/5ab4f4574d7f3e042261da702d493ee40d003356.1649168268.git.robin.murphy@arm.com
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  drivers/gpu/drm/msm/msm_drv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index 407b51cf6790..7322df9cf673 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -303,7 +303,7 @@ bool msm_use_mmu(struct drm_device *dev)
>         struct msm_drm_private *priv = dev->dev_private;
>
>         /* a2xx comes with its own MMU */
> -       return priv->is_a2xx || iommu_present(&platform_bus_type);
> +       return priv->is_a2xx || device_iommu_mapped(dev->dev);
>  }
>
>  static int msm_init_vram(struct drm_device *dev)
> --
> 2.35.1
>