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    Subject[PATCH 4.14 09/40] drm/mediatek: set DMA max segment size
    Date
    [ Upstream commit 070955558e820b9a89c570b91b1f21762f62b288 ]

    This driver requires imported PRIME buffers to appear contiguously in
    its IO address space. Make sure this is the case by setting the maximum
    DMA segment size to a more suitable value than the default 64KB.

    Signed-off-by: Alexandre Courbot <acourbot@chromium.org>
    Reviewed-by: Tomasz Figa <tfiga@chromium.org>
    Signed-off-by: CK Hu <ck.hu@mediatek.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/gpu/drm/mediatek/mtk_drm_drv.c | 35 ++++++++++++++++++++++++--
    drivers/gpu/drm/mediatek/mtk_drm_drv.h | 2 ++
    2 files changed, 35 insertions(+), 2 deletions(-)

    diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
    index 4a89cd2e4f1c5..034b50080304f 100644
    --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
    +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
    @@ -185,6 +185,7 @@ static int mtk_drm_kms_init(struct drm_device *drm)
    struct mtk_drm_private *private = drm->dev_private;
    struct platform_device *pdev;
    struct device_node *np;
    + struct device *dma_dev;
    int ret;

    if (!iommu_present(&platform_bus_type))
    @@ -242,7 +243,29 @@ static int mtk_drm_kms_init(struct drm_device *drm)
    goto err_component_unbind;
    }

    - private->dma_dev = &pdev->dev;
    + dma_dev = &pdev->dev;
    + private->dma_dev = dma_dev;
    +
    + /*
    + * Configure the DMA segment size to make sure we get contiguous IOVA
    + * when importing PRIME buffers.
    + */
    + if (!dma_dev->dma_parms) {
    + private->dma_parms_allocated = true;
    + dma_dev->dma_parms =
    + devm_kzalloc(drm->dev, sizeof(*dma_dev->dma_parms),
    + GFP_KERNEL);
    + }
    + if (!dma_dev->dma_parms) {
    + ret = -ENOMEM;
    + goto err_component_unbind;
    + }
    +
    + ret = dma_set_max_seg_size(dma_dev, (unsigned int)DMA_BIT_MASK(32));
    + if (ret) {
    + dev_err(dma_dev, "Failed to set DMA segment size\n");
    + goto err_unset_dma_parms;
    + }

    /*
    * We don't use the drm_irq_install() helpers provided by the DRM
    @@ -252,13 +275,16 @@ static int mtk_drm_kms_init(struct drm_device *drm)
    drm->irq_enabled = true;
    ret = drm_vblank_init(drm, MAX_CRTC);
    if (ret < 0)
    - goto err_component_unbind;
    + goto err_unset_dma_parms;

    drm_kms_helper_poll_init(drm);
    drm_mode_config_reset(drm);

    return 0;

    +err_unset_dma_parms:
    + if (private->dma_parms_allocated)
    + dma_dev->dma_parms = NULL;
    err_component_unbind:
    component_unbind_all(drm->dev, drm);
    err_config_cleanup:
    @@ -269,9 +295,14 @@ err_config_cleanup:

    static void mtk_drm_kms_deinit(struct drm_device *drm)
    {
    + struct mtk_drm_private *private = drm->dev_private;
    +
    drm_kms_helper_poll_fini(drm);
    drm_atomic_helper_shutdown(drm);

    + if (private->dma_parms_allocated)
    + private->dma_dev->dma_parms = NULL;
    +
    component_unbind_all(drm->dev, drm);
    drm_mode_config_cleanup(drm);
    }
    diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.h b/drivers/gpu/drm/mediatek/mtk_drm_drv.h
    index c3378c452c0a0..445dd45e65ebc 100644
    --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.h
    +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.h
    @@ -56,6 +56,8 @@ struct mtk_drm_private {
    } commit;

    struct drm_atomic_state *suspend_state;
    +
    + bool dma_parms_allocated;
    };

    extern struct platform_driver mtk_ddp_driver;
    --
    2.20.1


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