Messages in this thread | | | Date | Mon, 30 Jan 2023 18:21:54 +0000 | Subject | Re: [PATCH v2 1/8] iommu: Decouple iommu_present() from bus ops | From | Robin Murphy <> |
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On 2023-01-30 17:31, Jason Gunthorpe wrote: > On Thu, Jan 26, 2023 at 06:26:16PM +0000, Robin Murphy wrote: >> Much as I'd like to remove iommu_present(), the final remaining users >> are proving stubbornly difficult to clean up, so kick that can down >> the road and just rework it to preserve the current behaviour without >> depending on bus ops. >> >> Signed-off-by: Robin Murphy <robin.murphy@arm.com> >> --- > > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> > > This below might help. You might need to ask Thierry for help on the > problematic stuff in tegra. Really we should finish the series here > and organize things so that the domain allocation is defered until a > client is present.
mrk_drm doesn't even allocate, it relies on the DMA API domain; it also only runs on DT systems where IOMMU dependency ordering has been enforced by core code for a very long time now. I sent a patch simply removing that check back at the time of the rest of my iommu_present() cleanup, and it just got resoundingly ignored :(
Thanks, Robin.
> https://lore.kernel.org/linux-iommu/20220106022053.2406748-1-baolu.lu@linux.intel.com/ > > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c > index cd5b18ef79512c..e5c257e41f4933 100644 > --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c > +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c > @@ -353,9 +353,6 @@ static int mtk_drm_kms_init(struct drm_device *drm) > if (drm_firmware_drivers_only()) > return -ENODEV; > > - if (!iommu_present(&platform_bus_type)) > - return -EPROBE_DEFER; > - > pdev = of_find_device_by_node(private->mutex_node); > if (!pdev) { > dev_err(drm->dev, "Waiting for disp-mutex device %pOF\n", > @@ -709,6 +706,9 @@ static int mtk_drm_probe(struct platform_device *pdev) > int ret; > int i; > > + if (!device_iommu_mapped(dev)) > + return -EPROBE_DEFER; > + > private = devm_kzalloc(dev, sizeof(*private), GFP_KERNEL); > if (!private) > return -ENOMEM;
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