Re: [PATCH 2/2] smc91x: remove ARM hack for unaligned 16-bit writes
From: Nicolas Pitre <nico@fluxnic.net>
Date: 2016-08-25 18:14:59
Also in:
linux-arm-kernel, lkml
On Thu, 25 Aug 2016, Arnd Bergmann wrote:
The ARM specific I/O operations are almost the same as the generic ones, with the exception of the SMC_outw macro that works around a problem of some platforms that cannot write to 16-bit registers at an address that is not 32-bit aligned. By inspection, I found that this is handled already in the register abstractions for almost all cases, the exceptions being SMC_SET_MAC_ADDR() and SMC_SET_MCAST(). I assume that all platforms that require the hack for the other registers also need it here, so the ones listed explictly here are the only ones that work correctly, while the other ones either don't need the hack at all, or they will set an incorrect MAC address (which can often go unnoticed).
Probably that all PXA based platforms that use the SMC91x with 32-bit accesses need this. The others simply wired only 16 data lines, or only 8 like the Neponset. However I no longer have the concerned hardware and can't test it.
quoted hunk
This changes the two macros that set the unaligned registers to use 32-bit writes if possible, which should do the right thing in all combinations. The ARM specific SMC_outw gets removed as a consequence. The only difference between the ARM behavior and the default is the selection of the LED settings. The fact that we have different defaults based on the CPU architectures here is a bit suspicious, but probably harmless, and I have no plan of touching that. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/net/ethernet/smsc/smc91x.h | 50 +++++++++++++++++++++++--------------- 1 file changed, 30 insertions(+), 20 deletions(-)diff --git a/drivers/net/ethernet/smsc/smc91x.h b/drivers/net/ethernet/smsc/smc91x.h index 22333477d0b5..908473d9ede0 100644 --- a/drivers/net/ethernet/smsc/smc91x.h +++ b/drivers/net/ethernet/smsc/smc91x.h@@ -58,6 +58,7 @@ #define SMC_inw(a, r) readw((a) + (r)) #define SMC_inl(a, r) readl((a) + (r)) #define SMC_outb(v, a, r) writeb(v, (a) + (r)) +#define SMC_outw(v, a, r) writew(v, (a) + (r)) #define SMC_outl(v, a, r) writel(v, (a) + (r)) #define SMC_insw(a, r, p, l) readsw((a) + (r), p, l) #define SMC_outsw(a, r, p, l) writesw((a) + (r), p, l)@@ -65,19 +66,6 @@ #define SMC_outsl(a, r, p, l) writesl((a) + (r), p, l) #define SMC_IRQ_FLAGS (-1) /* from resource */ -/* We actually can't write halfwords properly if not word aligned */ -static inline void SMC_outw(u16 val, void __iomem *ioaddr, int reg) -{ - if ((machine_is_mainstone() || machine_is_stargate2() || - machine_is_pxa_idp()) && reg & 2) { - unsigned int v = val << 16; - v |= readl(ioaddr + (reg & ~2)) & 0xffff; - writel(v, ioaddr + (reg & ~2)); - } else { - writew(val, ioaddr + reg); - } -} - #elif defined(CONFIG_SH_SH4202_MICRODEV) #define SMC_CAN_USE_8BIT 0@@ -1029,18 +1017,40 @@ static const char * chip_ids[ 16 ] = { #define SMC_SET_MAC_ADDR(lp, addr) \ do { \ - SMC_out16(addr[0]|(addr[1] << 8), ioaddr, ADDR0_REG(lp)); \ - SMC_out16(addr[2]|(addr[3] << 8), ioaddr, ADDR1_REG(lp)); \ - SMC_out16(addr[4]|(addr[5] << 8), ioaddr, ADDR2_REG(lp)); \ + if (SMC_32BIT(lp)) { \ + SMC_outl((addr[0] )|(addr[1] << 8) | \ + (addr[2] << 16)|(addr[3] << 24), \ + ioaddr, ADDR0_REG(lp)); \ + } else { \ + SMC_out16(addr[0]|(addr[1] << 8), ioaddr, \ + ADDR0_REG(lp)); \ + SMC_out16(addr[2]|(addr[3] << 8), ioaddr, \ + ADDR1_REG(lp)); \ + } \ + SMC_out16(addr[4]|(addr[5] << 8), ioaddr, \ + ADDR2_REG(lp)); \ } while (0) #define SMC_SET_MCAST(lp, x) \ do { \ const unsigned char *mt = (x); \ - SMC_out16(mt[0] | (mt[1] << 8), ioaddr, MCAST_REG1(lp)); \ - SMC_out16(mt[2] | (mt[3] << 8), ioaddr, MCAST_REG2(lp)); \ - SMC_out16(mt[4] | (mt[5] << 8), ioaddr, MCAST_REG3(lp)); \ - SMC_out16(mt[6] | (mt[7] << 8), ioaddr, MCAST_REG4(lp)); \ + if (SMC_32BIT(lp)) { \ + SMC_outl((mt[0] ) | (mt[1] << 8) | \ + (mt[2] << 16) | (mt[3] << 24), \ + ioaddr, MCAST_REG1(lp)); \ + SMC_outl((mt[4] ) | (mt[5] << 8) | \ + (mt[6] << 16) | (mt[7] << 24), \ + ioaddr, MCAST_REG3(lp)); \ + } else { \ + SMC_out16(mt[0] | (mt[1] << 8), \ + ioaddr, MCAST_REG1(lp)); \ + SMC_out16(mt[2] | (mt[3] << 8), \ + ioaddr, MCAST_REG2(lp)); \ + SMC_out16(mt[4] | (mt[5] << 8), \ + ioaddr, MCAST_REG3(lp)); \ + SMC_out16(mt[6] | (mt[7] << 8), \ + ioaddr, MCAST_REG4(lp)); \ + } \ } while (0) #define SMC_PUT_PKT_HDR(lp, status, length) \-- 2.9.0