Re: [RFC/RFT] b43: Allow PIO mode to be selected at module load

[Michael Buesch <mb@bu3sch.de>]

On Thursday 10 December 2009 17:27:57 Larry Finger wrote:
> If a user encounters the "Fatal DMA Problem" with a BCM43XX device, and
> still wishes 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 option for the module.
> 
> 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>
> ---
> 
> 
> Index: wireless-testing/drivers/net/wireless/b43/Kconfig
> ===================================================================
> --- wireless-testing.orig/drivers/net/wireless/b43/Kconfig
> +++ wireless-testing/drivers/net/wireless/b43/Kconfig
> @@ -79,10 +79,11 @@ 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.
> +# Technically, this is only needed on PCMCIA and SDIO devices; but some LP PHYs
> +# cannot do DMA properly.
>  config B43_PIO
>  	bool
> -	depends on B43 && (B43_SDIO || B43_PCMCIA || B43_FORCE_PIO)
> +	depends on B43
>  	select SSB_BLOCKIO
>  	default y

Just remove the kconfig entry, too. ;)
Add the select SSB_BLOCKIO to CONFIG_B43

> @@ -137,12 +138,4 @@ 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.
> Index: wireless-testing/drivers/net/wireless/b43/Makefile
> ===================================================================
> --- wireless-testing.orig/drivers/net/wireless/b43/Makefile
> +++ wireless-testing/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
> Index: wireless-testing/drivers/net/wireless/b43/b43.h
> ===================================================================
> --- wireless-testing.orig/drivers/net/wireless/b43/b43.h
> +++ wireless-testing/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 b4
>  
>  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)));
> Index: wireless-testing/drivers/net/wireless/b43/main.c
> ===================================================================
> --- wireless-testing.orig/drivers/net/wireless/b43/main.c
> +++ wireless-testing/drivers/net/wireless/b43/main.c
> @@ -102,6 +102,9 @@ int b43_modparam_verbose = B43_VERBOSITY
>  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(stru
>  			       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) {
> @@ -4353,11 +4356,9 @@ static int b43_wireless_core_init(struct
>  
>  	if ((dev->dev->bus->bustype == SSB_BUSTYPE_PCMCIA) ||
>  	    (dev->dev->bus->bustype == SSB_BUSTYPE_SDIO) ||
> -	    B43_FORCE_PIO) {
> -		dev->__using_pio_transfers = 1;
> +	    dev->__using_pio_transfers) {

No, check for modparam_pio here instead of __using_pio_transfers.

>  		err = b43_pio_init(dev);
>  	} else {
> -		dev->__using_pio_transfers = 0;

and don't remove that here.

>  		err = b43_dma_init(dev);
>  	}
>  	if (err)
> @@ -4827,6 +4828,8 @@ static int b43_one_core_attach(struct ss
>  	wldev->wl = wl;
>  	b43_set_status(wldev, B43_STAT_UNINIT);
>  	wldev->bad_frames_preempt = modparam_bad_frames_preempt;
> +	if (modparam_pio)
> +		wldev->__using_pio_transfers = 1;

And remove this hunk.

>  	INIT_LIST_HEAD(&wldev->list);
>  
>  	err = b43_wireless_core_attach(wldev);



-- 
Greetings, Michael.