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SubjectRe: [PATCH] smc91x: remove ARM hack for unaligned 16-bit writes
Date
On Thursday, August 25, 2016 11:37:43 PM CEST Russell King - ARM Linux wrote:
> On Thu, Aug 25, 2016 at 08:02:35PM +0200, Robert Jarzmik wrote:
> > Arnd Bergmann <arnd@arndb.de> writes:
> /*
> + * Any 16-bit access is performed with two 8-bit accesses if the hardware
> + * can't do it directly. Most registers are 16-bit so those are mandatory.
> + */
> +#define SMC_outw_b(x, a, r) \
> + do { \
> + unsigned int __val16 = (x); \
> + unsigned int __reg = (r); \
> + SMC_outb(__val16, a, __reg); \
> + SMC_outb(__val16 >> 8, a, __reg + (1 << SMC_IO_SHIFT)); \
> + } while (0)
> +
> +#define SMC_inw_b(a, r) \
> + ({ \
> + unsigned int __val16; \
> + unsigned int __reg = r; \
> + __val16 = SMC_inb(a, __reg); \
> + __val16 |= SMC_inb(a, __reg + (1 << SMC_IO_SHIFT)) << 8; \
> + __val16; \
> + })
> +
> +/*
> * Define your architecture specific bus configuration parameters here.
> */
>
> @@ -55,10 +76,30 @@
> #define SMC_IO_SHIFT (lp->io_shift)
>
> #define SMC_inb(a, r) readb((a) + (r))
> -#define SMC_inw(a, r) readw((a) + (r))
> +#define SMC_inw(a, r) \
> + ({ \
> + unsigned int __smc_r = r; \
> + SMC_16BIT(lp) ? readw((a) + __smc_r) : \
> + SMC_8BIT(lp) ? SMC_inw_b(a, __smc_r) : \
> + ({ BUG(); 0; }); \
> + })
> +

I think this breaks machines that declare a device that just lists
SMC91X_USE_32BIT but not SMC91X_USE_16BIT. Right now, the way this
is interpreted is to use 32-bit accessors for most things, but
not avoiding 16-bit reads.

That is a bit fishy though, and we could instead change the platform
data to always set both SMC91X_USE_32BIT and SMC91X_USE_16BIT.

The affected platforms are DT based machines with 32-bit I/O and
these board files:

arch/arm/mach-pxa/idp.c: .flags = SMC91X_USE_32BIT | SMC91X_USE_DMA | SMC91X_NOWAIT,
arch/arm/mach-pxa/xcep.c: .flags = SMC91X_USE_32BIT | SMC91X_NOWAIT | SMC91X_USE_DMA,
arch/arm/mach-realview/core.c: .flags = SMC91X_USE_32BIT | SMC91X_NOWAIT,
arch/blackfin/mach-bf561/boards/cm_bf561.c: .flags = SMC91X_USE_32BIT | SMC91X_NOWAIT,
arch/blackfin/mach-bf561/boards/ezkit.c: .flags = SMC91X_USE_32BIT | SMC91X_NOWAIT,

Arnd

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