Re: [PATCH v2 2/4] thunderbolt: Handle ring interrupt by reading intr status

[Mika Westerberg <mika.westerberg@linux.intel.com>]

Hi,

On Tue, Aug 03, 2021 at 07:34:54AM -0500, Sanjay R Mehta wrote:
> From: Sanjay R Mehta <sanju.mehta@amd.com>
> 
> As per USB4 spec by default "Disable ISR Auto-Clear" bit is set to 0,
> and the Tx/Rx ring interrupt status is needs to be cleared.
> 
> Hence handling it by reading the "Interrupt status" register in the ISR.
> 
> Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
> Signed-off-by: Sanjay R Mehta <sanju.mehta@amd.com>
> ---
>  drivers/thunderbolt/nhi.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
> index ef01aa6..7ad2202 100644
> --- a/drivers/thunderbolt/nhi.c
> +++ b/drivers/thunderbolt/nhi.c
> @@ -373,11 +373,25 @@ 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)
> +{
> +	if (!(ring->nhi->pdev->vendor == PCI_VENDOR_ID_INTEL)) {
> +		if (ring->is_tx)
> +			ioread32(ring->nhi->iobase
> +				 + REG_RING_NOTIFY_BASE);
> +		else
> +			ioread32(ring->nhi->iobase
> +				 + REG_RING_NOTIFY_BASE
> +				 + 4 * (ring->nhi->hop_count / 32));
> +	}
> +}

I'm now playing with this series on Intel hardware. I wanted to check
from you whether the AMD controller implements the Auto-Clear feature? I
mean if we always clear bit 17 of the Host Interface Control register do
you still need to call the above or it is cleared automatically?

I'm hoping that we could make this work on all controllers without too
many special cases ;-)