24.10.2019 14:50, Thierry Reding пишет:
On Sun, Jun 23, 2019 at 08:37:41PM +0300, Dmitry Osipenko wrote:
On ARM32 we don't want any of the clients device to be backed by the implicit domain, simply because we can't afford such a waste on older Tegra SoCs that have very few domains available in total. The recent IOMMU support addition for the Video Decoder hardware uncovered the problem that an unfortunate drivers probe order results in the DRM driver probe failure if CONFIG_ARM_DMA_USE_IOMMU=y due to a shortage of IOMMU domains caused by the implicit backing. The host1x_client_register() is a common function that is invoked by all of the relevant DRM drivers during theirs probe and hence it is convenient to remove the implicit backing there, resolving the problem.
Signed-off-by: Dmitry Osipenko digetx@gmail.com
drivers/gpu/host1x/bus.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
I don't really want to do this in a central place like this. If we really do need this, why can't we do it in the individual drivers?
Why do you want to duplicate the same action for each driver instead of doing it in a single common place?
we already call host1x_client_iommu_attach() from all the drivers and that detaches from the IOMMU as well. So I'm not sure I understand why this is needed.
Wish you could ask that couple months ago. I'll try to refresh the details.