[PATCH] powerpc/config: Disable the 4KiB erase granularity of SPI flash

[Zhiqiang Hou]

Hi David,

Thanks for your comments.

> -----Original Message-----
> From: David Laight [mailto:David.Laight at ACULAB.COM]
> Sent: 2016年4月9日 0:01
> To: Zhiqiang Hou <zhiqiang.hou at nxp.com>; Scott Wood <oss at buserror.net>;
> linuxppc-dev at lists.ozlabs.org; benh at kernel.crashing.org; paulus at samba.org;
> mpe at ellerman.id.au
> Cc: Mingkai Hu <mingkai.hu at nxp.com>
> Subject: RE: [PATCH] powerpc/config: Disable the 4KiB erase granularity of SPI
> flash
> 
> From: Zhiqiang Hou
> > Sent: 07 April 2016 04:17
> ...
> > > Is there a reason specific to 85xx to have a different default than
> > > every other platform except lpc18xx?  The description of
> > > MTD_SPI_NOR_USE_4K_SECTORS acknowledges that erase speed is a
> > > tradeoff.  Why is that concern more compelling on 85xx than elsewhere?
> > >
> >
> > I don't want to specify 85xx, but configs of fsl. I'm still confusing
> > about so many configs. Will add other platforms if necessary.
> >
> > For this patch, it takes about 13 mins to erase 64MiB by subsector
> > erase command (4KiB per time), but takes 2 mins by sector erase
> > command(64KiB per time). It is conspicuous decrease. Why it uses the
> > 4KiB granularity by default, what's the benefit?
> 
> Should it be doing 64K erases followed by 0 to 15 4K erases for any final fragment?

When will this situation come up?

Thanks,
Zhiqiang