Re: [PATCH 2/4] thunderbolt: Handle INTR when Disable ISR auto clear bit set

[Sanjay R Mehta <sanmehta@amd.com>]

On 8/2/2021 8:52 PM, Mika Westerberg wrote:
> [CAUTION: External Email]
> 
> Hi,
> 
> On Mon, Aug 02, 2021 at 07:58:18AM -0500, Sanjay R Mehta wrote:
>> From: Sanjay R Mehta <sanju.mehta@amd.com>
>>
>> when the "Disable ISR Auto-Clear" bit is set, the Tx/Rx ring
>> interrupt status is not cleared. Hence handling it by setting
>> the "Interrupt status clear" register to clear the
>> corresponding Tx/Rx ring interrupt.
> 
> I think REG_DMA_MISC_INT_AUTO_CLEAR which is bit 2 in that register is
> actually Intel specific and not the same as in the USB4 spec bit 17. I
> guess the AMD controller works fine as is if this bit (2) is not set? If
> that's the case we can simply limit this behavior for Intel controllers.
> 

Yes, you are right Mika. With bit 17 it's working for us and we didn't
wanted to break Intel's functionality , hence we added this change which
works for both :).

Yes, as you suggested, we can limit this to Intel controllers.

Will send the changes accordingly.

Thanks,
Sanjay

>>
>> Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
>> Signed-off-by: Sanjay R Mehta <sanju.mehta@amd.com>
>> ---
>>  drivers/thunderbolt/nhi.c   | 26 +++++++++++++++++++++++++-
>>  include/linux/thunderbolt.h |  1 +
>>  2 files changed, 26 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
>> index d7d9c4b..63bbabf 100644
>> --- a/drivers/thunderbolt/nhi.c
>> +++ b/drivers/thunderbolt/nhi.c
>> @@ -74,7 +74,11 @@ static void ring_interrupt_active(struct tb_ring *ring, bool active)
>>               if (!(misc & REG_DMA_MISC_INT_AUTO_CLEAR)) {
>>                       misc |= REG_DMA_MISC_INT_AUTO_CLEAR;
>>                       iowrite32(misc, ring->nhi->iobase + REG_DMA_MISC);
>> -             }
>> +                     misc = ioread32(ring->nhi->iobase + REG_DMA_MISC);
>> +                     if (misc & REG_DMA_MISC_INT_AUTO_CLEAR)
>> +                             ring->nhi->is_intr_autoclr = true;
>> +             } else
>> +                     ring->nhi->is_intr_autoclr = true;
>>
>>               ivr_base = ring->nhi->iobase + REG_INT_VEC_ALLOC_BASE;
>>               step = index / REG_INT_VEC_ALLOC_REGS * REG_INT_VEC_ALLOC_BITS;
>> @@ -377,11 +381,31 @@ void tb_ring_poll_complete(struct tb_ring *ring)
>>  }
>>  EXPORT_SYMBOL_GPL(tb_ring_poll_complete);
>>
>> +static void check_and_clear_intr_status(struct tb_ring *ring, int int_pos)
>> +{
>> +     u32 value;
>> +
>> +     if (!ring->nhi->is_intr_autoclr) {
>> +             value = ioread32(ring->nhi->iobase
>> +                                      + REG_RING_NOTIFY_BASE
>> +                                      + 4 * (int_pos / 32));
>> +             iowrite32(value, ring->nhi->iobase
>> +                       + (REG_RING_NOTIFY_BASE + 8)
>> +                       + 4 * (int_pos / 32));
>> +     }
>> +}
>> +
>>  static irqreturn_t ring_msix(int irq, void *data)
>>  {
>>       struct tb_ring *ring = data;
>>
>>       spin_lock(&ring->nhi->lock);
>> +
>> +     if (ring->is_tx)
>> +             check_and_clear_intr_status(ring, 0);
>> +     else
>> +             check_and_clear_intr_status(ring, ring->nhi->hop_count);
>> +
>>       spin_lock(&ring->lock);
>>       __ring_interrupt(ring);
>>       spin_unlock(&ring->lock);
>> diff --git a/include/linux/thunderbolt.h b/include/linux/thunderbolt.h
>> index e7c96c3..bbe7c7e 100644
>> --- a/include/linux/thunderbolt.h
>> +++ b/include/linux/thunderbolt.h
>> @@ -478,6 +478,7 @@ struct tb_nhi {
>>       struct tb_ring **rx_rings;
>>       struct ida msix_ida;
>>       bool going_away;
>> +     bool is_intr_autoclr;
>>       struct work_struct interrupt_work;
>>       u32 hop_count;
>>  };
>> --
>> 2.7.4