linux-kernel - Re: [PATCH V2 2/2] ARM: l2c: AM437x: Introduce support for cache filter programming

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Date:	Sat, 3 Jan 2015 09:34:46 -0600
From:	Nishanth Menon <nm@...com>
To:	Tomasz Figa <tomasz.figa@...il.com>
CC:	Tony Lindgren <tony@...mide.com>,
	Russell King <linux@....linux.org.uk>,
	linux-omap <linux-omap@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Santosh <ssantosh@...nel.org>, Sekhar Nori <nsekhar@...com>
Subject: Re: [PATCH V2 2/2] ARM: l2c: AM437x: Introduce support for cache
 filter programming

On 15:40-20150103, Tomasz Figa wrote:
> Hi Nishanth,
> 
> 2015-01-03 2:43 GMT+09:00 Nishanth Menon <nm@...com>:
> > AM437x generation of processors support programming the PL310 L2Cache
> > controller's address filter start and end registers using a secure
> > montior service.
> 
> typo: s/montior/monitor/
> 
> [snip]

Uggh.. yes indeed. I will post a v3 updating the comments. If the
following is ok.
> 
> > +               base = omap4_get_l2cache_base();
> > +               filter_start = (reg == L310_ADDR_FILTER_START) ? val :
> > +                              readl_relaxed(base + L310_ADDR_FILTER_START);
> > +               filter_end = (reg == L310_ADDR_FILTER_END) ? val :
> > +                              readl_relaxed(base + L310_ADDR_FILTER_END);
> > +               omap_smc1_2(AM43X_MON_L2X0_SETFILTER_INDEX, filter_start,
> > +                           filter_end);
> > +               return;
> 
> I don't have any significant comments about this patch in particular,
> but just noticed that you need to do read-backs here (and the typo
> thanks to the spell checker of my mailing app). Maybe you should
> consider switching to the .configure() API I introduced in my series?
> This would let you get rid of the hardcoded static mapping.

Yeah, I have two choices there.. Either I provide the fundamental
write function for the generic l2c code to use OR I provide a
duplicate of resultant l2c_configure(aux write) + l2c310_configure.

To allow for reuse of improvements or anything like errata
implementations in the future, OMAP L2C implementation has chosen to provide the
low level code and allow the higherlevel configure/write/whatever of the
future to stay in arch/arm/mm/cache-l2x0.c. The write_sec operation is
not too complicated enough to warrant a replication of l2c310_configure.

So, I prefer the current implementation than providing a .configure
handler for outer_cache.configure from SoC level.

Let me know if anyone has a strong objection to this.

-- 
Regards,
Nishanth Menon
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