[PATCH 2/2] b43: fix DMA on some bugged hardware

[Michael Büsch]

On Wed, 10 Aug 2011 18:45:57 +0200
Rafał Miłecki <zajec5 at gmail.com> wrote:

> W dniu 10 sierpnia 2011 18:33 użytkownik Michael Büsch <m at bues.ch> napisał:
> > On Wed, 10 Aug 2011 18:11:28 +0200
> >> diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c
> >> index 0953ce1..9a2b678 100644
> >> --- a/drivers/net/wireless/b43/dma.c
> >> +++ b/drivers/net/wireless/b43/dma.c
> >> @@ -174,7 +174,10 @@ static void op64_fill_descriptor(struct b43_dmaring *ring,
> >>       addrhi = (((u64) dmaaddr >> 32) & ~SSB_DMA_TRANSLATION_MASK);
> >>       addrext = (((u64) dmaaddr >> 32) & SSB_DMA_TRANSLATION_MASK)
> >>           >> SSB_DMA_TRANSLATION_SHIFT;
> >> -     addrhi |= ring->dev->dma.translation;
> >> +     if (ring->dev->dma.translation_in_low)
> >> +             addrlo |= ring->dev->dma.translation;
> >> +     else
> >> +             addrhi |= ring->dev->dma.translation;
> >>       if (slot == ring->nr_slots - 1)
> >>               ctl0 |= B43_DMA64_DCTL0_DTABLEEND;
> >>       if (start)
> >> @@ -656,10 +659,12 @@ static int alloc_initial_descbuffers(struct b43_dmaring *ring)
> >>  static int dmacontroller_setup(struct b43_dmaring *ring)
> >>  {
> >>       int err = 0;
> >> +     int tmp;
> >>       u32 value;
> >>       u32 addrext;
> >>       u32 trans = ring->dev->dma.translation;
> >>       bool parity = ring->dev->dma.parity;
> >> +     u32 addrs[2];
> >>
> >>       if (ring->tx) {
> >>               if (ring->type == B43_DMA_64BIT) {
> >> @@ -673,12 +678,14 @@ static int dmacontroller_setup(struct b43_dmaring *ring)
> >>                       if (!parity)
> >>                               value |= B43_DMA64_TXPARITYDISABLE;
> >>                       b43_dma_write(ring, B43_DMA64_TXCTL, value);
> >> -                     b43_dma_write(ring, B43_DMA64_TXRINGLO,
> >> -                                   (ringbase & 0xFFFFFFFF));
> >> -                     b43_dma_write(ring, B43_DMA64_TXRINGHI,
> >> -                                   ((ringbase >> 32) &
> >> -                                    ~SSB_DMA_TRANSLATION_MASK)
> >> -                                   | trans);
> >> +
> >> +                     addrs[0] = ringbase & 0xFFFFFFFF;
> >> +                     addrs[1] = ringbase >> 32;
> >> +                     tmp = ring->dev->dma.translation_in_low ? 0 : 1;
> >> +                     addrs[tmp] &= ~SSB_DMA_TRANSLATION_MASK;
> >> +                     addrs[tmp] |= trans;
> >> +                     b43_dma_write(ring, B43_DMA64_TXRINGLO, addrs[0]);
> >> +                     b43_dma_write(ring, B43_DMA64_TXRINGHI, addrs[1]);
> >>               } else {
> >>                       u32 ringbase = (u32) (ring->dmabase);
> >>
> >> @@ -710,12 +717,15 @@ static int dmacontroller_setup(struct b43_dmaring *ring)
> >>                       if (!parity)
> >>                               value |= B43_DMA64_RXPARITYDISABLE;
> >>                       b43_dma_write(ring, B43_DMA64_RXCTL, value);
> >> -                     b43_dma_write(ring, B43_DMA64_RXRINGLO,
> >> -                                   (ringbase & 0xFFFFFFFF));
> >> -                     b43_dma_write(ring, B43_DMA64_RXRINGHI,
> >> -                                   ((ringbase >> 32) &
> >> -                                    ~SSB_DMA_TRANSLATION_MASK)
> >> -                                   | trans);
> >> +
> >> +                     addrs[0] = ringbase & 0xFFFFFFFF;
> >> +                     addrs[1] = ringbase >> 32;
> >> +                     tmp = ring->dev->dma.translation_in_low ? 0 : 1;
> >> +                     addrs[tmp] &= ~SSB_DMA_TRANSLATION_MASK;
> >> +                     addrs[tmp] |= trans;
> >> +                     b43_dma_write(ring, B43_DMA64_RXRINGLO, addrs[0]);
> >> +                     b43_dma_write(ring, B43_DMA64_RXRINGHI, addrs[1]);
> >> +
> >>                       b43_dma_write(ring, B43_DMA64_RXINDEX, ring->nr_slots *
> >>                                     sizeof(struct b43_dmadesc64));
> >>               } else {
> >> @@ -1052,6 +1062,21 @@ static int b43_dma_set_mask(struct b43_wldev *dev, u64 mask)
> >>       return 0;
> >>  }
> >
> >
> > This doesn't look correct to me for several reasons:
> >
> > In the fill-op the address is not masked correctly with the translation mask.
> > In both the fill-op and both ring setups, the actual address extension bits
> > are always taken from the address's high word. I guess the extension should
> > be the low word bits for devices where we use the low word. That's the only
> > thing that would make sense. But hey, it's not that we have sane hardware here.
> > So this has to be checked.
> 
> Ouch, yeah, you should be right (according to common sense of design).
> 
> Unfortunately, on my machine, kernel provides low addresses for DMA purposes:
> 0x1f310000
> 0x1f318000
> 0x1f31c000
> 
> Can I ask/hack kernel to offer b43 addresses starting with 0x4... or
> 0x8... (or 0xc...)?

I'm not sure I understand..
Are you actually saying that those shiny new devices are total crap
in that their 64bit DMA engine can only do real-life-30bit, because they
completely fucked up the extension bits?
Did you try to fix the extension according to my suggestion? Does that
break stuff?

-- 
Greetings, Michael.