Re: [PATCH 01/16] gpio: dwapb: Use modern PM macros

[Jisheng Zhang <jszhang@kernel.org>]

On Wed, Aug 20, 2025 at 10:04:39PM +0300, Andy Shevchenko wrote:
> On Wed, Aug 20, 2025 at 8:11 PM Michael Büsch <mb@bues.ch> wrote:
> >
> > On Wed, 20 Aug 2025 19:54:44 +0300
> > Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> >
> > > > The dwapb_context structure is always embedded into struct
> > > > dwapb_gpio_port to simplify code. Sure this brings a tiny 36 bytes
> > > > data overhead for !CONFIG_PM_SLEP.
> > >
> > > I don't think it's a good approach to add a lot of data for peanuts in
> > > case of PM_SLEEP=n.
> >
> > It wastes 36 bytes in case of PM=n.
> 
> ...per port.
> 
> > The driver currently allocates the struct with kzalloc and stores a pointer to it
> > in case of PM=y.
> > So this probably has an overhead in the same order of magnitude (pointer +
> > malloc overhead/alignment/fragmentation) in case of PM=y now.
> 
> ...per driver.

Before the patch, struct dwapb_context *ctx is also per port.

> 
> So, I can't say it's equal, but I leave this to maintainers to decide,

What in my mind now: this is linux rather than RTOS. After greping the
the arm/arm64/riscv dts dir, the max port number is 6, the berlin2q
soc families, so this means current we have wasted 216 bytes memory which
is trivial compared to the system memory.