linux-kernel - Re: [PATCH v3 0/6] uio_pruss cleanup and platform support

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Date:	Thu, 4 Oct 2012 09:54:33 -0400
From:	Matt Porter <mporter@...com>
To:	Philipp Zabel <pza@...gutronix.de>
Cc:	Linux DaVinci Kernel List 
	<davinci-linux-open-source@...ux.davincidsp.com>,
	Russell King <linux@....linux.org.uk>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Hans J. Koch" <hjk@...sjkoch.de>,
	Linux ARM Kernel List <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 0/6] uio_pruss cleanup and platform support

On Thu, Oct 04, 2012 at 03:35:53PM +0200, Philipp Zabel wrote:
> On Thu, Oct 04, 2012 at 08:42:53AM -0400, Matt Porter wrote:
> > > I think the generic SRAM/genalloc driver (https://lkml.org/lkml/2012/9/7/282)
> > > could be useful to map the L3RAM on Davinci.
> > > With the gen_pool lookup patch (https://lkml.org/lkml/2012/9/7/284) the
> > > uio_pruss driver could then use the gen_pool_find_by_phys() (or
> > > of_get_named_gen_pool() for initialization from device tree) to
> > > retrieve the struct gen_pool*.
> > > 
> > > This way you could avoid handing it over via platform data and you could
> > > get rid of arch/arm/mach-davinci/{sram.c,include/mach/sram.h} completely.
> > 
> > I did miss the gen_pool_find_by_phys() call in that series. That does
> > look useful. I actually mentioned your series in an earlier posting
> > since I like it,
> 
> That I did miss.
> 
> > but since the initialization of the driver was inherently
> > tied to DT it's not usable for DaVinci that's just starting to convert
> > to DT and needs !DT support as well.
> 
> There should be no dependency on DT in the sram driver. It just requests
> and remaps the first given iomem resource and creates a gen_pool from that.
> This should work just as well for the !DT case.
> Maybe it's just my choice of patch series subject gave you that
> impression? If there's a real issue for !DT, I should fix it.

*sigh*, I see now. I looked at v2 and got wrapped up in the DT use case
and missed your platform device support. I think it will work just fine
for us to use in a "phase 2" of this work, replacing the backend of
davinci sram allocation with this as Sekhar seems to be open to. 

> > I do see it moving to your driver exclusively, but I wanted to make this
> > series focused on only getting rid of the private SRAM API using the
> > existing pdata framework that's already there. I think once
> > gen_pool_find_by_phys() goes upstream we can switch to that and get the
> > address from a resource in the !DT case. I guess we should see if Sekhar
> > would like to see this happen in two steps or just have us depend on
> > the gen_pool_find_by_phys() patch now.
> 
> Thanks, I'm glad you are aware of the sram driver and consider it useful.
> 
> > BTW, I was going to post a patch for your driver to allow
> > configurability of the allocation order, but have been busy with other
> > things.  We'll eventually need that when switching to it as the
> > hardcoded page size order isn't going to work for all cases.
> 
> Good point.

I think this is the only blocker to DaVinci adopting it once it goes
upstream. I can add a patch in your driver thread if that helps.

-Matt
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