Hi Brian,
On Fri, 11 Sep 2015 15:46:03 -0700
Brian Norris <computersforpeace@xxxxxxxxx> wrote:
> On Thu, Sep 03, 2015 at 09:06:48AM +0200, Boris Brezillon wrote:
> > The USER_DATA register cannot be accessed using byte accessors on A13
> > SoCs, thus triggering a bug when using memcpy_toio on this register.
> > Declare two helper macros to convert an OOB buffer into a suitable
> > USER_DATA value and vice-versa.
> >
> > This patch also fixes an error in the oob_required logic (some OOB data
> > are not written even if the user required it) by removing the
> > oob_required condition, which is perfectly valid since the core already
> > fill ->oob_poi with FFs when oob_required is false.
> >
> > Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> > Cc: <stable@xxxxxxxxxxxxxxx> # 3.19+
> > Fixes: 1fef62c1423b ("mtd: nand: add sunxi NAND flash controller support")
> >
> > ---
> > Changes since v2:
> > - add the NFC_USER_DATA_TO_BUF() macro and rename NFC_USER_DATA() into
> > NFC_BUF_TO_USER_DATA()
> > - rework the commit message
> >
> > Changes since v1:
> > - drop the !oob_required conditional path
> > - replace endianness conversions by a macro relying on byte shifting
> > operations
> > ---
> > drivers/mtd/nand/sunxi_nand.c | 33 ++++++++++++++++-----------------
> > 1 file changed, 16 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
> > index f97a58d..f9b5a4c 100644
> > --- a/drivers/mtd/nand/sunxi_nand.c
> > +++ b/drivers/mtd/nand/sunxi_nand.c
> > @@ -147,6 +147,17 @@
> > #define NFC_ECC_MODE GENMASK(15, 12)
> > #define NFC_RANDOM_SEED GENMASK(30, 16)
> >
> > +/* NFC_USER_DATA helper macros */
> > +#define NFC_BUF_TO_USER_DATA(buf) ((buf)[0] | ((buf)[1] << 8) | \
> > + ((buf)[2] << 16) | ((buf)[3] << 24))
>
> I thought you were treading on thin ice with bit-shifting a uint8_t, but
> it appears that C integer promotion rules are on your side here. (The
> result of this operation should be an int.)
Yep. I used to cast the first element to an u32 to deal with such use
cases until I realized it was actually not needed ;-).
>
> > +#define NFC_USER_DATA_TO_BUF(buf, val) \
>
> BTW, why do you need this macro? It's currently unused. Just as an
> example? I can take it as-is if you'd like, but I was curious why you
> felt the need for this in v3, especially for -stable.
You're right, it's not needed in this patch. I'll remove it from this
commit and re-introduce it when needed.
Best Regards,
Boris
--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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