Re: [virtio-dev] [PATCH] virtio-mmio: Specify wait needed in driver during reset

[Jason Wang <jasowang@redhat.com>]

å 2021/7/22 äå5:19, Srivatsa Vaddagiri åé:
> This is following up on the discussion we had earlier on MMIO reset 
> behavior:
>
> https://lists.oasis-open.org/archives/virtio-dev/202107/msg00012.html 
> <https://lists.oasis-open.org/archives/virtio-dev/202107/msg00012.html>
>
> Suggesting below change to spec to make it explicit what's expected in 
> driver. If this is accepted, I will follow up with a patch to Linux 
> driver.
>
> ===
>
> Device reset is accomplished by writing 0 to Status register. 
> Explicitly note
> that a driver needs to wait on Status register read returning 0 before 
> assuming that
> device reset operation is complete.
> Signed-off-by: Srivatsa Vaddagiri <svaddagi@qti.qualcomm.com>



I wonder if it deserves a feature bit.


Thanks


> diff --git a/content.tex b/content.tex
> index 5c70a3c..7631be4 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -1985,6 +1985,10 @@ \subsubsection{Device 
> Initialization}\label{sec:Virtio Transport Options / Virti
> Âand if its value is zero (0x0) MUST abort initialization and
> ÂMUST NOT access any other register.
> +After writing 0 to \field{Status}, the driver MUST wait for a read of
> +\field{Status} to return 0 before proceeding with the remaining steps of
> +initializing the device.
> +
> ÂDrivers not expecting shared memory MUST NOT use the shared
> Âmemory registers.
>
>
> ---
>
> Qualcomm Innovation Center, Inc. is submitting the attached "feedback" 
> as a non-member to the virtio-dev mailing list for consideration and 
> inclusion.