[PATCH AUTOSEL 5.2 28/76] drm/mediatek: set DMA max segment size

Sasha Levin
2019-08-29T18:14:18Z

From: Alexandre Courbot <acourbot@chromium.org>

[ 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 8b18a00a58c7e..c021d4c8324f5 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
@@ -213,6 +213,7 @@ 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))
@@ -275,7 +276,29 @@ 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
@@ -285,13 +308,16 @@ 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:
@@ -302,9 +328,14 @@ static int mtk_drm_kms_init(struct drm_device *drm)

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 598ff3e704465..e03fea12ff598 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.h
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.h
@@ -51,6 +51,8 @@ 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