[U-Boot] [PATCH 00/18] Support for eMMC partitioning and related fixes

[Joakim Tjernlund]

Diego Santa Cruz <Diego.SantaCruz at spinetix.com> wrote on 2014/11/28 
12:12:56:
> 
> Hi,
> 
> > -----Original Message-----
> > From: Joakim Tjernlund [mailto:joakim.tjernlund at transmode.se]
> > Sent: Friday, November 28, 2014 11:05 AM
> > To: Diego Santa Cruz
> > Cc: panto at antoniou-consulting.com; u-boot at lists.denx.de
> > Subject: Re: [U-Boot] [PATCH 00/18] Support for eMMC partitioning and 
related
> > fixes
> > >
> > > I have the need to hardware partition eMMC devices from U-Boot along
> > > with setting enhanced and reliable write attributes.
> > >
> > > This series of patches adds this support to U-Boot via a new mmc
> > > API, a few new members of struct mmc and a new mmc sub-command. It
> > > also features several fixes to the eMMC hardware partition support. 
I
> > > have tested this with Micron eMMC 4.41 parts and it is working as
> > > expected.
> > 
> > This is really great, thanks.
> 
> Good to know it may be useful to other people.
> 
> > 
> > I do wonder(I am fairly new to eMMC) about 512B emulation.
> > In mmc utils there is a:
> > mmc disable 512B emulation <device>
> >         Set the eMMC data sector size to 4KB by disabling emulation on
> > <device>.
> > 
> > I am hoping 4K size will increase performance and reliability?
> > Could you add this feature too to your patch set?
> >
> 
> I think this was introduced in eMMC 4.51. I do not have any 4.51 devices 
at hand to test with but I am not sure there would be any performance 
benefit to issue reads and writes in the 4KB large sector size. All eMMC 
devices I've seen write in chunks much larger than 4 KB internally anyhow 
(the ones I'm using now have a superpage size of 32 KB). Writes should be 
aligned to the superpage size to get good performance.
> 

It is in eMMC 4.5 and I asked our eMMC supplier about 4KB, not only does 
4KB increase performance somewhat,
it also has a significant impact on device life.

 Jocke