On Thu, Dec 07, 2023 at 04:51:01PM +0530, Manivannan Sadhasivam wrote: > On Thu, Dec 07, 2023 at 03:56:43PM +0530, Nitin Rawat wrote: > > > > > > On 12/7/2023 3:13 PM, Manivannan Sadhasivam wrote: > > > On Wed, Dec 06, 2023 at 03:02:04PM -1000, Bart Van Assche wrote: > > > > On 12/6/23 05:32, Manivannan Sadhasivam wrote: > > > > > On Wed, Dec 06, 2023 at 07:32:54PM +0530, Naresh Maramaina wrote: > > > > > > On 12/5/2023 10:41 PM, Bart Van Assche wrote: > > > > > > > On 12/4/23 21:58, Naresh Maramaina wrote: > > > > > > > > On 12/5/2023 12:30 AM, Bart Van Assche wrote: > > > > > > > > > On 12/4/23 06:30, Maramaina Naresh wrote: > > > > > > > > > > + /* This capability allows the host controller driver to > > > > > > > > > > use the PM QoS > > > > > > > > > > + * feature. > > > > > > > > > > + */ > > > > > > > > > > + UFSHCD_CAP_PM_QOS = 1 << 13, > > > > > > > > > > }; > > > > > > > > > > > > > > > > > > Why does it depend on the host driver whether or not PM QoS is > > > > > > > > > enabled? Why isn't it enabled unconditionally? > > > > > > > > > > > > > > > > For some platform vendors power KPI might be more important than > > > > > > > > random io KPI. Hence this flag is disabled by default and can be > > > > > > > > enabled based on platform requirement. > > > > > > > > > > > > > > How about leaving this flag out unless if a host vendor asks explicitly > > > > > > > for this flag? > > > > > > > > > > > > IMHO, instead of completely removing this flag, how about having > > > > > > flag like "UFSHCD_CAP_DISABLE_PM_QOS" which will make PMQOS enable > > > > > > by default and if some host vendor wants to disable it explicitly, > > > > > > they can enable that flag. > > > > > > Please let me know your opinion. > > > > > > > > That would result in a flag that is tested but that is never set by > > > > upstream code. I'm not sure that's acceptable. > > > > > > > > > > Agree. The flag shouldn't be introduced if there are no users. > > > > > > > > If a vendor wants to disable this feature, then the driver has to be modified. > > > > > That won't be very convenient. So either this has to be configured through sysfs > > > > > or Kconfig if flexibility matters. > > > > > > > > Kconfig sounds worse to me because changing any Kconfig flag requires a > > > > modification of the Android GKI kernel. > > > > > > > > > > Hmm, ok. Then I think we can have a sysfs hook to toggle the enable switch. > > > > Hi Bart, Mani > > > > How about keeping this feature enabled by default and having a module > > parameter to disable pmqos feature if required ? > > > > Module params not encouraged these days unless there are no other feasible > options available. Yeah, one of the problem with module param is that we can't have different settings for two two UFS controllers. Anyways, this setting need not be a module param, there is nothing special about this setting that is tied to module loading (driver probe) time, AFAICT. Thanks, Pavan
