Re: [PATCH 2/3] ARM: bus: da8xx-syscfg: new driver

Laurent Pinchart
2016-10-19T09:06:21Z

Hi Bartosz,

On Wednesday 19 Oct 2016 10:26:57 Bartosz Golaszewski wrote:
> 2016-10-18 22:49 GMT+02:00 Laurent Pinchart:
> > On Monday 17 Oct 2016 18:30:49 Bartosz Golaszewski wrote:
> >> Create the driver for the da8xx System Configuration and implement
> >> support for writing to the three Master Priority registers.
> >>
> >> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> [snip]
>
> >> +
> >> +Documentation:
> >> +OMAP-L138 (DA850) - http://www.ti.com/lit/ug/spruh82c/spruh82c.pdf
> >> +
> >> +Required properties:
> >> +
> >> +- compatible: "ti,da850-syscfg"
> >
> > Don't you need a reg property ?
>
> Yes, Kevin already pointed that out. I'll add it in v2. Same for [1/3].
>
> >> +Optional properties:
> >> +
> >> +The below properties are used to specify the priority of master
> >> peripherals.
> >> +They must be between 0-7 where 0 is the highest priority and 7 is the
> >> lowest.
> >> +
> >> +- ti,pri-arm-i: ARM_I port priority.
> >> +
> >> +- ti,pri-arm-d: ARM_D port priority.
> >> +
> >> +- ti,pri-upp: uPP port priority.
> >> +
> >> +- ti,pri-sata: SATA port priority.
> >> +
> >> +- ti,pri-pru0: PRU0 port priority.
> >> +
> >> +- ti,pri-pru1: PRU1 port priority.
> >> +
> >> +- ti,pri-edma30tc0: EDMA3_0_TC0 port priority.
> >> +
> >> +- ti,pri-edma30tc1: EDMA3_0_TC1 port priority.
> >> +
> >> +- ti,pri-edma31tc0: EDMA3_1_TC0 port priority.
> >> +
> >> +- ti,pri-vpif-dma-0: VPIF DMA0 port priority.
> >> +
> >> +- ti,pri-vpif-dma-1: VPIF DMA1 port priority.
> >> +
> >> +- ti,pri-emac: EMAC port priority.
> >> +
> >> +- ti,pri-usb0cfg: USB0 CFG port priority.
> >> +
> >> +- ti,pri-usb0cdma: USB0 CDMA port priority.
> >> +
> >> +- ti,pri-uhpi: HPI port priority.
> >> +
> >> +- ti,pri-usb1: USB1 port priority.
> >> +
> >> +- ti,pri-lcdc: LCDC port priority.
> >
> > I'm afraid this looks more like system configuration than hardware
> > description to me.
>
> While you're certainly right, this approach is already implemented in
> several other memory and bus drivers and it was also suggested by
> Sekhar in one of the tilcdc rev1 threads. There's also no real
> alternative that I know of.

The fact that other drivers get it wrong is no excuse for copying them :-)

> > There was a BoF session about how to support this kind of performance
> > knobs at ELCE last week:
> > https://openiotelceurope2016.sched.org/event/7rss/bof-linux-device-perfor
> > mance-framework-michael-turquette-baylibre :-)
>
> I know, I was there. ;)

That's why I mentioned it :-)

> Unfortunately it was just a discussion about potential approaches -
> there's no code yet.

Patches are welcome ;-)

--
Regards,

Laurent Pinchart