On Tue, Nov 01, 2022 at 04:34:21PM -0700, Stephen Boyd wrote: > We shouldn't be calling runtime PM APIs from within the genpd > enable/disable path for a couple reasons. [..][ > Upon closer inspection, calling runtime PM APIs like this in the GDSC > driver doesn't make sense. It was intended to make sure the GDSC for the > clock controller providing other GDSCs was enabled, specifically the > MMCX GDSC for the display clk controller on SM8250 (sm8250-dispcc), so > that GDSC register accesses succeeded. That will already happen because > we make the 'dev->pm_domain' a parent domain of each GDSC we register in > gdsc_register() via pm_genpd_add_subdomain(). When any of these GDSCs > are accessed, we'll enable the parent domain (in this specific case > MMCX). > It's correct that adding the GDSCs as subdomains for the device's parent-domain will ensure that enabling a GDSC will propagate up and turn on the (typically) rpmhpd resource. But the purpose for the explicit calls was to ensure that the clock controller itself is accessible. It's been a while since I looked at this, but iirc letting MMCX to turn off would cause the register access during dispcc probing to fail - similar to how clk_pm_runtime_get()/put() ensures the clock registers are accessible. Perhaps I misunderstood something in the process, or lost track of the actual issues? Regards, Bjorn
