b43: Allow PIO mode to be selected at module load

If userencounter the "Fatal DMA Problem" with a BCM43XX device, and
still wish to use b43 as the driver, their only option is to rebuild
the kernel with CONFIG_B43_FORCE_PIO. This patch removes this option and
allows PIO mode to be selected with a load-time parameter for the module.
Note that the configuration variable CONFIG_B43_PIO is also removed.

Once the DMA problem with the BCM4312 devices is solved, this patch will
likely be reverted.
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Tested-by: John Daiker <daikerjohn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/Kconfig

@@ -3,6 +3,7 @@ config B43
 	depends on SSB_POSSIBLE && MAC80211 && HAS_DMA
 	select SSB
 	select FW_LOADER
+	select SSB_BLOCKIO
 	---help---
 	  b43 is a driver for the Broadcom 43xx series wireless devices.
 
@@ -78,14 +79,6 @@ config B43_SDIO
 
 	  If unsure, say N.
 
-# Data transfers to the device via PIO
-# This is only needed on PCMCIA and SDIO devices. All others can do DMA properly.
-config B43_PIO
-	bool
-	depends on B43 && (B43_SDIO || B43_PCMCIA || B43_FORCE_PIO)
-	select SSB_BLOCKIO
-	default y
-
 config B43_NPHY
 	bool "Pre IEEE 802.11n support (BROKEN)"
 	depends on B43 && EXPERIMENTAL && BROKEN
@@ -137,12 +130,4 @@ config B43_DEBUG
 	  for production use.
 	  Only say Y, if you are debugging a problem in the b43 driver sourcecode.
 
-config B43_FORCE_PIO
-	bool "Force usage of PIO instead of DMA"
-	depends on B43 && B43_DEBUG
-	---help---
-	  This will disable DMA and always enable PIO instead.
 
-	  Say N!
-	  This is only for debugging the PIO engine code. You do
-	  _NOT_ want to enable this.

drivers/net/wireless/b43/Makefile

@@ -12,7 +12,7 @@ b43-y				+= xmit.o
 b43-y				+= lo.o
 b43-y				+= wa.o
 b43-y				+= dma.o
-b43-$(CONFIG_B43_PIO)		+= pio.o
+b43-y				+= pio.o
 b43-y				+= rfkill.o
 b43-$(CONFIG_B43_LEDS)		+= leds.o
 b43-$(CONFIG_B43_PCMCIA)	+= pcmcia.o

drivers/net/wireless/b43/b43.h

@@ -821,11 +821,9 @@ struct b43_wl {
 	/* The device LEDs. */
 	struct b43_leds leds;
 
-#ifdef CONFIG_B43_PIO
 	/* Kmalloc'ed scratch space for PIO TX/RX. Protected by wl->mutex. */
 	u8 pio_scratchspace[110] __attribute__((__aligned__(8)));
 	u8 pio_tailspace[4] __attribute__((__aligned__(8)));
-#endif /* CONFIG_B43_PIO */
 };
 
 static inline struct b43_wl *hw_to_b43_wl(struct ieee80211_hw *hw)
@@ -876,20 +874,9 @@ static inline void b43_write32(struct b43_wldev *dev, u16 offset, u32 value)
 
 static inline bool b43_using_pio_transfers(struct b43_wldev *dev)
 {
-#ifdef CONFIG_B43_PIO
 	return dev->__using_pio_transfers;
-#else
-	return 0;
-#endif
 }
 
-#ifdef CONFIG_B43_FORCE_PIO
-# define B43_FORCE_PIO	1
-#else
-# define B43_FORCE_PIO	0
-#endif
-
-
 /* Message printing */
 void b43info(struct b43_wl *wl, const char *fmt, ...)
     __attribute__ ((format(printf, 2, 3)));

drivers/net/wireless/b43/dma.c

@@ -1760,7 +1760,6 @@ void b43_dma_tx_resume(struct b43_wldev *dev)
 	b43_power_saving_ctl_bits(dev, 0);
 }
 
-#ifdef CONFIG_B43_PIO
 static void direct_fifo_rx(struct b43_wldev *dev, enum b43_dmatype type,
 			   u16 mmio_base, bool enable)
 {
@@ -1794,4 +1793,3 @@ void b43_dma_direct_fifo_rx(struct b43_wldev *dev,
 	mmio_base = b43_dmacontroller_base(type, engine_index);
 	direct_fifo_rx(dev, type, mmio_base, enable);
 }
-#endif /* CONFIG_B43_PIO */

drivers/net/wireless/b43/main.c

@@ -102,6 +102,9 @@ int b43_modparam_verbose = B43_VERBOSITY_DEFAULT;
 module_param_named(verbose, b43_modparam_verbose, int, 0644);
 MODULE_PARM_DESC(verbose, "Log message verbosity: 0=error, 1=warn, 2=info(default), 3=debug");
 
+static int modparam_pio;
+module_param_named(pio, modparam_pio, int, 0444);
+MODULE_PARM_DESC(pio, "enable(1) / disable(0) PIO mode");
 
 static const struct ssb_device_id b43_ssb_tbl[] = {
 	SSB_DEVICE(SSB_VENDOR_BROADCOM, SSB_DEV_80211, 5),
@@ -1786,8 +1789,8 @@ static void b43_do_interrupt_thread(struct b43_wldev *dev)
 			       dma_reason[4], dma_reason[5]);
 			b43err(dev->wl, "This device does not support DMA "
 			       "on your system. Please use PIO instead.\n");
-			b43err(dev->wl, "CONFIG_B43_FORCE_PIO must be set in "
-			       "your kernel configuration.\n");
+			b43err(dev->wl, "Unload the b43 module and reload "
+			       "with 'pio=1'\n");
 			return;
 		}
 		if (merged_dma_reason & B43_DMAIRQ_NONFATALMASK) {
@@ -4353,7 +4356,7 @@ static int b43_wireless_core_init(struct b43_wldev *dev)
 
 	if ((dev->dev->bus->bustype == SSB_BUSTYPE_PCMCIA) ||
 	    (dev->dev->bus->bustype == SSB_BUSTYPE_SDIO) ||
-	    B43_FORCE_PIO) {
+	    modparam_pio) {
 		dev->__using_pio_transfers = 1;
 		err = b43_pio_init(dev);
 	} else {

drivers/net/wireless/b43/pio.h

@@ -55,8 +55,6 @@
 #define B43_PIO_MAX_NR_TXPACKETS	32
 
 
-#ifdef CONFIG_B43_PIO
-
 struct b43_pio_txpacket {
 	/* Pointer to the TX queue we belong to. */
 	struct b43_pio_txqueue *queue;
@@ -169,42 +167,4 @@ void b43_pio_rx(struct b43_pio_rxqueue *q);
 void b43_pio_tx_suspend(struct b43_wldev *dev);
 void b43_pio_tx_resume(struct b43_wldev *dev);
 
-
-#else /* CONFIG_B43_PIO */
-
-
-static inline int b43_pio_init(struct b43_wldev *dev)
-{
-	return 0;
-}
-static inline void b43_pio_free(struct b43_wldev *dev)
-{
-}
-static inline void b43_pio_stop(struct b43_wldev *dev)
-{
-}
-static inline int b43_pio_tx(struct b43_wldev *dev,
-			     struct sk_buff *skb)
-{
-	return 0;
-}
-static inline void b43_pio_handle_txstatus(struct b43_wldev *dev,
-					   const struct b43_txstatus *status)
-{
-}
-static inline void b43_pio_get_tx_stats(struct b43_wldev *dev,
-					struct ieee80211_tx_queue_stats *stats)
-{
-}
-static inline void b43_pio_rx(struct b43_pio_rxqueue *q)
-{
-}
-static inline void b43_pio_tx_suspend(struct b43_wldev *dev)
-{
-}
-static inline void b43_pio_tx_resume(struct b43_wldev *dev)
-{
-}
-
-#endif /* CONFIG_B43_PIO */
 #endif /* B43_PIO_H_ */