[PATCH] dma: imx-sdma: Add ROM script addresses to driver

[s.hauer@pengutronix.de (Sascha Hauer)]

On Tue, Aug 20, 2013 at 08:53:42AM -0500, Matt Sealey wrote:
> You know what, I am really confused by this in the first place. Since
> when did the SDMA driver actually support ROM addresses in device tree
> anyway (referring your comments in the patch series) and when did it
> get removed? Why is platform data somehow now required in a driver and
> not being put in it's correct place in the device tree?

The SDMA driver never supported ROM script addresses when probed from
the devicetree. This was only ever supported with platform based
devices. With devicetree probing platform data never was and and is not
required.

> 
> Why require a firmware file for anything here, bugs notwithstanding?
> As far as I recall there were one or two in older tape-out i.MX6 (uart
> dma I think) and a few more in i.MX51 and i.MX53 early tapeouts. I was
> sure I saw some BSP commits that update the firmware to fix some bugs
> in production tape-outs (oddly they're seemingly not in the errata for
> any tape-out?). The ROM addresses should be in DT, and for those
> devices that now have platform_data glue hardcoding the vaues, they'll
> work. DT platforms won't.
> 
> I don't understand here how it's not possible to specify the ROM
> addresses in the DT for instance using the way regulators are handled
> (but I'd want to see reg used to specify the address and name instead
> of a custom properties in this case).

We could specify ROM addresses in the dt, but why should we do this? It
would just add more API between the kernel and the dt for no gain.

> 
> What I'd really like to see is the "waiting on a firmware that doesn't
> exist when there is a working ROM version of those scripts in the SoC"

Then this patch is for you. This is exactly what the patch solves.

> bug fixed properly, by using ROM addresses in DT - specifying the
> "wrong" addresses is a device tree bug for that board with that
> tape-out or users using the wrong device-tree. Then fudging
> platform_data for non-DT platforms makes sense in that they have no
> DTs. And when they are converted they will follow suit anyway -
> there's a path to take to get there that is really clear.
> 
> In this case it is just hardcoding one or two SoC and then leaving the
> rest tha tare actually device-tree compliant to use that abominable,
> OS-specific firmware path name property.. keeping the hangs. I'm
> really trying to figure out the intent and design process here,
> because from a perspective of getting more device tree support this
> really is stepping backwards via a hack to get a couple boards to
> work.

This patch is by no means board specific.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |