Re: [PATCH 7/9] hw/ide/ahci: trigger either error IRQ or regular IRQ, not both

[John Snow <jsnow@redhat.com>]

On Fri, Apr 28, 2023 at 9:23 AM Niklas Cassel <nks@flawful.org> wrote:
>
> From: Niklas Cassel <niklas.cassel@wdc.com>
>
> According to AHCI 1.3.1, 5.3.8.1 RegFIS:Entry, if ERR_STAT is set,
> we jump to state ERR:FatalTaskfile, which will raise a TFES IRQ
> unconditionally, regardless if the I bit is set in the FIS or not.
>
> Thus, we should never raise a normal IRQ after having sent an error
> IRQ.
>
> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>

ACK - and thanks for the spec pointers.

> ---
>  hw/ide/ahci.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
> index 2a59d0e0f5..d88961b4c0 100644
> --- a/hw/ide/ahci.c
> +++ b/hw/ide/ahci.c
> @@ -891,11 +891,10 @@ static bool ahci_write_fis_d2h(AHCIDevice *ad, bool d2h_fis_i)
>      pr->tfdata = (ad->port.ifs[0].error << 8) |
>          ad->port.ifs[0].status;
>
> +    /* TFES IRQ is always raised if ERR_STAT is set, regardless of I bit. */
>      if (d2h_fis[2] & ERR_STAT) {
>          ahci_trigger_irq(ad->hba, ad, AHCI_PORT_IRQ_BIT_TFES);
> -    }
> -
> -    if (d2h_fis_i) {
> +    } else if (d2h_fis_i) {
>          ahci_trigger_irq(ad->hba, ad, AHCI_PORT_IRQ_BIT_DHRS);
>      }
>
> --
> 2.40.0
>