On Wed, Feb 25, 2026 at 11:26:52PM +0530, Ekansh Gupta wrote: > > > On 2/24/2026 4:14 AM, Dmitry Baryshkov wrote: > > On Tue, Feb 24, 2026 at 12:38:58AM +0530, Ekansh Gupta wrote: > >> Introduce a built-in compute context-bank (CB) bus used by the Qualcomm > >> DSP accelerator (QDA) driver to represent DSP CB devices that require > >> IOMMU configuration. This separates the CB bus from the QDA driver and > >> allows QDA to remain a loadable module while the bus is always built-in. > > Why? What is the actual problem that you are trying to solve? > Bus needs to be built-in as it is being used by iommu driver. I'll add more > details here.
It's an implementation detail. Start your commit message with the description of the issue or a problem that you are solving. > > > >> A new bool Kconfig symbol DRM_ACCEL_QDA_COMPUTE_BUS is added and is > > Don't describe the patch contents. Please. > Ack. > > > >> selected by the main DRM_ACCEL_QDA driver. The parent accel Makefile is > >> updated to descend into the QDA directory for both built-in and module > >> builds so that the CB bus is compiled into vmlinux while the driver > >> remains modular. > >> > >> The CB bus is registered at postcore_initcall() time and is exposed to > >> the IOMMU core through iommu_buses[] in the same way as the Tegra > >> host1x context-bus. This enables later patches to create CB devices on > >> this bus and obtain IOMMU domains for them. > > Note, there is nothing QDA-specific in this patch. Please explain, why > > the bus is QDA-specific? Can we generalize it? > I needed a custom bus here to use for the compute cb devices for iommu > configurations, I don't see any reason to keep it QDA-specific. The only > requirement > is that this should be enabled built in whenever QDA is enabled. Why? FastRPC uses platform_bus. You need to explain, why it's not correct. > > But if I keep it generic, where should this be placed? Should it be accel(or > drm?) specific? drivers/base? Or drivers/iommu? That would totally depend on the issue description. E.g. can we use the same code for host1x? -- With best wishes Dmitry
