Messages in this thread | | | Date | Thu, 7 Dec 2023 15:56:43 +0530 | Subject | Re: [PATCH V2 1/3] ufs: core: Add CPU latency QoS support for ufs driver | From | Nitin Rawat <> |
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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 ?
Regards, Nitin
> > - Mani > >> Thanks, >> >> Bart. >
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