RE: [PATCH v3 1/1]mmc: implemented eMMC4.4 enhanced area feature

From: Dong, Chuanxiao
Date: Fri Jan 21 2011 - 04:12:16 EST


Hi Chris,
> /sys/devices/.../mmc_host/mmcX/mmcX:XXXX/enhanced_area_size
> > > > +Date: January 2011
> > > > +Contact: Chuanxiao Dong <chuanxiao.dong@xxxxxxxxx>
> > > > +Description:
> > > > + Enhanced area is a new feature defined in eMMC4.4 standard.
> eMMC4.4
> > > or
> > > > + later card can support such feature. This kind of area can help to
> > > > + improve the card performance. If the feature is enabled, this
> attribute
> > > > + will indicate the size of enhanced data area. If not, this attribute
> > > > + will be -EINVAL. Unit KByte. Format decimal.
> > >
> > > This is still wrapped at > 80 columns.
> > Sorry for that. I have set the textwidth=80 for vim, not understand why this is still
> wrapped at >80 columns... I know checkpatch.pl can help us to find the style
> problem, and is there some other script which can help find the style problem of
> Document or how can I avoid such errors?
>
> checkpatch.pl will warn about >80 chars, so that should be fine on its own.
I have used the checkpatch.pl to check this patch, and no error or warning found....

>
> > > Oh, and let's mention the units of _offset and _size in the comment in
> > > card.h.
> >
> > Chris, you mean the type of _offset and _size? I think the 64bits number for
> _offset is enough, also the 32bits number for _size since the units of _size is Kbytes.
> Any suggestions on that?
>
> Ah, I wasn't clear -- I meant the bytes/kilobytes units, not the data type
> sizes. e.g.:
>
> + size_t enhanced_area_size; /* Units: KB */
I think the units of _offset and _size should be easy for user to understand, so just choose the Byte for _offset and Kbyte for _size...
And as spec said, the _size is (ENH_SIZE_MULT_2 << 16 + ENH_SIZE_MULT_1 << 8 + ENH_SIZE_MULT_0) x HC_WP_GRP_SIZE x HC_ERASE_GPR_SIZE x 512kBytes. It must be Kbytes aligned. That is another reason to choose it.
What do you think?

Thanks
Chuanxiao
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