Re: [PATCH net-next v3 2/3] bus: mhi: host: pci_generic: enumerate IP_CTRL channel for Sierra EM919x/EM929x

[Loic Poulain]

On Fri, Aug 7, 2026 at 11:51 PM Peter Hunt <peter.hunt@xxxxxxxxxxxx> wrote:
>
> IP_CTRL is a standard Qualcomm MHI control channel (channels 18/19) that
> carries the host serial control lines (DTR/RTS) to the modem; it is not
> Sierra-specific. It was not enumerated for any device in pci_generic, so
> the host had no way to drive those signals.
>
> Enumerate it in the Sierra em919x channel config (shared by the EM919x
> and EM929x) using the control event ring. This is the device the change
> was tested against; other Qualcomm modem configs that expose IP_CTRL can
> enable it the same way, since the mhi_wwan_ctrl DTR support that consumes
> it is device-agnostic and binds purely by channel name.
>
> Signed-off-by: Peter Hunt <peter.hunt@xxxxxxxxxxxx>

Reviewed-by: Loic Poulain <loic.poulain@xxxxxxxxxxxxxxxx>

> ---
>  drivers/bus/mhi/host/pci_generic.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/bus/mhi/host/pci_generic.c b/drivers/bus/mhi/host/pci_generic.c
> index 0d0d9c7ffa4b..ba47dd153837 100644
> --- a/drivers/bus/mhi/host/pci_generic.c
> +++ b/drivers/bus/mhi/host/pci_generic.c
> @@ -728,6 +728,8 @@ static const struct mhi_channel_config mhi_sierra_em919x_channels[] = {
>         MHI_CHANNEL_CONFIG_DL(13, "MBIM", 128, 0),
>         MHI_CHANNEL_CONFIG_UL(14, "QMI", 32, 0),
>         MHI_CHANNEL_CONFIG_DL(15, "QMI", 32, 0),
> +       MHI_CHANNEL_CONFIG_UL(18, "IP_CTRL", 32, 0),
> +       MHI_CHANNEL_CONFIG_DL(19, "IP_CTRL", 32, 0),
>         MHI_CHANNEL_CONFIG_UL(32, "DUN", 32, 0),
>         MHI_CHANNEL_CONFIG_DL(33, "DUN", 32, 0),
>         MHI_CHANNEL_CONFIG_HW_UL(100, "IP_HW0", 512, 1),
> --
> 2.43.0
>