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SubjectRe: [PATCH] drm/mediatek: make imported PRIME buffers contiguous
On Wed, Jul 24, 2019 at 2:49 PM CK Hu <ck.hu@mediatek.com> wrote:
>
> Hi, Alexandre:
>
> On Tue, 2019-07-23 at 14:34 +0900, Alexandre Courbot wrote:
> > 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 better value than the default 64K on the DMA
> > device, and use said DMA device when importing PRIME buffers.
> >
> > Signed-off-by: Alexandre Courbot <acourbot@chromium.org>
> > ---
> > drivers/gpu/drm/mediatek/mtk_drm_drv.c | 47 ++++++++++++++++++++++++--
> > drivers/gpu/drm/mediatek/mtk_drm_drv.h | 2 ++
> > 2 files changed, 46 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> > index 95fdbd0fbcac..4ad4770fab13 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 +276,27 @@ 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)
> > + goto err_component_unbind;
>
> return with ret = 0?

Oops, indeed.

>
> > +
> > + 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 +306,16 @@ 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 +326,14 @@ 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);
> > }
> > @@ -320,6 +349,18 @@ static const struct file_operations mtk_drm_fops = {
> > .compat_ioctl = drm_compat_ioctl,
> > };
> >
> > +/*
> > + * We need to override this because the device used to import the memory is
> > + * not dev->dev, as drm_gem_prime_import() expects.
> > + */
> > +struct drm_gem_object *mtk_drm_gem_prime_import(struct drm_device *dev,
> > + struct dma_buf *dma_buf)
> > +{
> > + struct mtk_drm_private *private = dev->dev_private;
> > +
> > + return drm_gem_prime_import_dev(dev, dma_buf, private->dma_dev);
> > +}
> > +
>
> I think this part should be an independent patch which fixup
> 119f5173628aa ("drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.")

I have split this patch and sent a v2.

Thanks,
Alex.

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