Re: [PATCH 6/8] bus: mhi: core: Add support for processing priority of event ring

Manivannan Sadhasivam
2021-06-24T14:50:12Z

On Thu, Jun 24, 2021 at 04:40:38PM +0200, Greg KH wrote:
> On Thu, Jun 24, 2021 at 07:54:53PM +0530, Manivannan Sadhasivam wrote:
> > On Thu, Jun 24, 2021 at 03:53:33PM +0200, Greg KH wrote:
> > > On Mon, Jun 21, 2021 at 09:46:14PM +0530, Manivannan Sadhasivam wrote:
> > > > From: Hemant Kumar <hemantk@codeaurora.org>
> > > >
> > > > Event ring priorities are currently set to 1 and are unused.
> > > > Default processing priority for event rings is set to regular
> > > > tasklet. Controllers can choose to use high priority tasklet
> > > > scheduling for certain event rings critical for processing such
> > > > as ones transporting control information if they wish to avoid
> > > > system scheduling delays for those packets. In order to support
> > > > these use cases, allow controllers to set event ring priority to
> > > > high.
> > > >
> > > > Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
> > > > Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
> > > > Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > > > Link: https://lore.kernel.org/r/1624053903-24653-2-git-send-email-bbhatt@codeaurora.org
> > > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > > > ---
> > > > drivers/bus/mhi/core/init.c | 3 +--
> > > > drivers/bus/mhi/core/main.c | 9 +++++++--
> > > > include/linux/mhi.h | 2 +-
> > > > 3 files changed, 9 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> > > > index c81b377fca8f..444676034bf0 100644
> > > > --- a/drivers/bus/mhi/core/init.c
> > > > +++ b/drivers/bus/mhi/core/init.c

[...]

> > That's because, "1" was used from the beginning by the controller drivers
> > as the regular priority. And I thought of using "0" as high priority so
> > that we can leave the controller drivers unmodified.
>
> There's no problem modifying everyone, how much work is that?
>

I thought of minimizing the diff if we can avoid...err

> > > Shouldn't this be a boolean, or if not, an enumerated type so that
> > > people can read the code over time?
> > >
> >
> > Bhaumik proposed an enum but I wanted 0/1 so that the controller drivers
> > can be untouched. Also, I don't see any immediate requirement for other
> > priorities.
> >
> > Will make it a bool then.
>
> Rename it when you change it so that you know you catch all existing
> users.
>

Okay. Bhaumik, can you please use the enum (as you did)?

Thanks,
Mani

> thanks,
>
> greg k-h