Re: [PATCH 00/15] musb: Add support for the Allwinner sunxi musb controller

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Hi,

On 03/10/2015 06:41 PM, Maxime Ripard wrote:
On Mon, Mar 09, 2015 at 09:40:13PM +0100, Hans de Goede wrote:
Hi All,

This patch set has been a while in the making, so I'm very happy to present
the end result here, and I hope everyone likes it.

Before talking about merging this there are 2 things which I would like to
point out:

a) The musb controller in the sunxi SoCs uses some SRAM which needs to be
mapped to the musb controller by poking some bits in the SRAM controller,
just like the EMAC patches which were send a while back I've chosen to use
syscon for this, actually 2 of the patches in this set come directly from the
SRAM mapping patchset for the EMAC.

I know that Maxime is not 100% in favor of using syscon:
http://lists.infradead.org/pipermail/linux-arm-kernel/2015-January/320221.html

But I disagree with his arguments for writing a special driver for the SRAM
controller:

And I disagree with your disagreement :)

1) syscon was specifically designed for global system control registers like
this and is fine to use as long as there are no conflicts where 1 bit is of
interest to multiple drivers, and there is no such conflict here

No. Syscon has been designed for being lazy.

This is a huge abstraction non-sense. You have to put all the logic of
dealing with some external register layout in clients drivers,
including dealing with the different revisions/SoC that are different
from that aspect, and duplicating that code across all client drivers.

2) Maxime's other arguments seem to boil down to it would be nice / prettier
to have a specific driver for this, without really proving a hard need for
such a driver. But writing such a driver is going to be a lot of work, and
we've a ton of other work to do, and as said there is no real need for a
separate driver, syscon works fine for this.

Actually, I already wrote some prototype for this. I'll clean this up
and send it tonight/tomorrow.

Ok, lets see your prototype and then we'll go from there.

Regards,

Hans
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