Re: [PATCH v2 5/5] ARM: dts: ls1021a-tsn: Use the DSPI controller in poll mode

On Wed, Sep 11, 2019 at 8:34 AM Shawn Guo [off-list ref] wrote:

On Tue, Aug 27, 2019 at 09:16:39PM +0300, Vladimir Oltean wrote:

quoted

On Tue, 27 Aug 2019 at 21:13, Mark Brown [off-list ref] wrote:

quoted

On Tue, Aug 27, 2019 at 09:06:14PM +0300, Vladimir Oltean wrote:

quoted

On Tue, 27 Aug 2019 at 21:05, Mark Brown [off-list ref] wrote:

quoted

On Mon, Aug 26, 2019 at 04:10:51PM +0300, Vladimir Oltean wrote:

quoted

quoted

quoted

I noticed you skipped applying this patch, and I'm not sure that Shawn
will review it/take it.
Do you have a better suggestion how I can achieve putting the DSPI
driver in poll mode for this board? A Kconfig option maybe?

quoted

quoted

DT changes go through the relevant platform trees, not the
subsystem trees, so it's not something I'd expect to apply.

quoted

But at least is it something that you expect to see done through a
device tree change?

Well, it's not ideal - if it performs better all the time the
driver should probably just do it unconditionally.  If there's
some threashold where it tends to perform better then the driver
should check for that but IIRC it sounds like the interrupt just
isn't at all helpful here.

I can't seem to find any situation where it performs worse. Hence my
question on whether it's a better idea to condition this behavior on a
Kconfig option rather than a DT blob which may or may not be in sync.

DT is a description of hardware not condition for software behavior,
where module parameter is usually used for.

+1

DT says the interrupt line is wired.
The driver should know if it should make use of the interrupt, or not.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds