* H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> [230116 15:29]: > Hi, > > > Am 16.01.2023 um 15:51 schrieb Tony Lindgren <tony@xxxxxxxxxxx>: > > > > Hi, > > > > * Adam Ford <aford173@xxxxxxxxx> [230116 14:16]: > >> Would it make sense to make this default in the omap3.dtsi file and > >> enable them in the individual boards that need it? > > > > In general disabling the unused devices by default for omaps will break > > the power management. The disabled devices are completely ignored by the > > kernel, and the devices are left to whatever the bootloader state might > > be. > > Yes, indeed. See my further clarification based on what Adam commented too, I was thinking status = "disabled" at the ti-sysc parent level. > > For SoCs using firmware to manage devices it's a bit different story > > however. The firmware can still idle disabled devices based on a > > late_initcall for example, even if the kernel knows nothing about the > > disabled devices. > > But how can we then handle all devices being "okay" by default and > eating up more dma channels than are available? 1. Set the child device (not the ti-sysc node) with status = "disabled" in the board specific file as needed 2. Use /delete-property/ for dma channels in the board specific file if the device is in use but does not need dma 3. Or if this is a generic problem, we could disable dma by default for some devices > We can't put all under power management AND dma by default. > > Or can dma channel usage be postponed until the device is really used? Sure. Regards, Tony
