On Thu, May 22, 2014 at 02:56:52PM +0200, Thomas Petazzoni wrote: > The pxa3xx_nand driver currently uses __raw_writel() and __raw_readl() > to access I/O registers. However, those functions do not do any > endianness swapping, which means that they won't work when the CPU > runs in big-endian but the I/O registers are little endian, which is > the common situation for ARM systems running big endian. > > Since __raw_writel() and __raw_readl() do not include any memory > barriers and the pxa3xx_nand driver can only be compiled for ARM > platforms, the closest I/o accessors functions that do endianess > swapping are writel_relaxed() and readl_relaxed().
With any luck, the *_relaxed() accessors will be implemented uniformly on all architectures soon. I believe there's an outstanding patch series for this out on LKML. > This patch has been verified to work on Armada XP GP: without the > patch, the NAND is not detected when the kernel runs big endian while > it is properly detected when the kernel runs little endian. With the > patch applied, the NAND is properly detected in both situations > (little and big endian). > > Signed-off-by: Thomas Petazzoni <[email protected]> > Cc: <[email protected]> # v3.13+ > --- > This patch does not fix a regression introduced by a previous commit, > but is still necessary for stable to allow NAND to work properly on > ARM big endian platforms. The 3.13 starting point was chosen because > the support for big endian on modern ARM systems was added in this > kernel release. > > Signed-off-by: Thomas Petazzoni <[email protected]> Two sign-offs for the price of one! ;) Pushed to l2-mtd.git. Thanks! Brian > --- > drivers/mtd/nand/pxa3xx_nand.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c > index 7588fe2..3003611 100644 > --- a/drivers/mtd/nand/pxa3xx_nand.c > +++ b/drivers/mtd/nand/pxa3xx_nand.c > @@ -127,10 +127,10 @@ > > /* macros for registers read/write */ > #define nand_writel(info, off, val) \ > - __raw_writel((val), (info)->mmio_base + (off)) > + writel_relaxed((val), (info)->mmio_base + (off)) > > #define nand_readl(info, off) \ > - __raw_readl((info)->mmio_base + (off)) > + readl_relaxed((info)->mmio_base + (off)) > > /* error code and state */ > enum { -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
