[U-Boot] [PATCH] mmc:dcache: Cache line size aligned internal MMC buffers

Lukasz Majewski
2011-08-23T08:42:51Z

Hi Mike,

On Mon, 22 Aug 2011 12:08:42 -0400
Mike Frysinger <vapier@gentoo.org> wrote:

> On Monday, August 22, 2011 03:29:52 Lukasz Majewski wrote:
> > On Fri, 19 Aug 2011 11:35:50 -0400 Mike Frysinger wrote:
> > > On Friday, August 19, 2011 11:28:18 Lukasz Majewski wrote:
> > > > On Fri, 19 Aug 2011 09:57:10 -0400 Mike Frysinger wrote:
> > > > > On Friday, August 19, 2011 05:25:13 Lukasz Majewski wrote:
> > > > > also, what is the code size increase with your patch ?
> > > >
> > > > Code size overhead (s5p_goni target):
> > > > Without proposed changes: 167928 B (u-boot.bin)
> > > > With changes: 168208 B (u-boot.bin)
> > > >
> > > > Delta: 280 B
> > >
> > > np if it gives significant (more than system noise) speedups. any
> > > details on that ?
> >
> > No tests performed yet. The goal of those patches is to preserve the
> > MMC subsystem functionality when dcache is enabled (the ext_csd[512]
> > corruption is observed with d-cache enabled).
>
> so you're papering over a bug in some controller's cache handling ?
> shouldnt you fix the controller in question by having it flush its
> caches ? aligning random buffers to make cache issues "go away" isnt
> the right way for anything. -mike

Please look into the following patch:
http://patchwork.ozlabs.org/patch/110576/

It seems that only flushing/invalidating buffers is not enough.

--
Best regards,

Lukasz Majewski

Samsung Poland R&D Center
Platform Group