[rt2x00-users] [RFC 2/9] rt2x00: convert to threaded interrupts

[Helmut Schaa]

Am Montag 05 Juli 2010 schrieb Ivo Van Doorn:
> On Mon, Jul 5, 2010 at 6:20 PM, Helmut Schaa
> <helmut.schaa at googlemail.com> wrote:

[...]

> > +       /* Enable interrupts again. */
> > +       rt2x00pci_register_read(rt2x00dev, CSR8, &reg);
> > +       reg &= ~rt2x00dev->irqmask[0];
> > +       rt2x00pci_register_write(rt2x00dev, CSR8, reg);
> > +
> 
> Cant this be replaced with:
> rt2400pci_toggle_irq(rt2x00dev, STATE_RADIO_IRQ_ON)
> That way we keep the IRQ changing code in one location,
> and we keep the code clearer compared to using masks which
> obscure the real action.

[...]
> > +       /* Disable interrupts, will be enabled again in the interrupt thread. */
> > +       rt2x00pci_register_read(rt2x00dev, CSR8, &reg);
> > +       reg |= rt2x00dev->irqmask[0];
> > +       rt2x00pci_register_write(rt2x00dev, CSR8, reg);
> 
> Cant this be replaced with:
> rt2400pci_toggle_irq(rt2x00dev, STATE_RADIO_IRQ_OFF)

Yeah, I also had the same thought but during my tests the device got stuck
when using rt2800pci_toggle_irq (only tested rt2800pci).

The trigger was clearly the following:

 428         /*
 429          * When interrupts are being enabled, the interrupt registers
 430          * should clear the register to assure a clean state.
 431          */
 432         if (state == STATE_RADIO_IRQ_ON) {
 433                 rt2800_register_read(rt2x00dev, INT_SOURCE_CSR, &reg);
 434                 rt2800_register_write(rt2x00dev, INT_SOURCE_CSR, reg);
 435         }

So, reenabling the interrupts at the end of the interrupt thread handler
didn't work correctly. However, I don't have an explanation why that would
make the device stuck.

Of course we could also extend rt2800pci_toggle_irq with a parameter to not
force the flush of the INT_SOURCE_CSR register.

Thanks for the quick reply,
Helmut