linux-kernel - Re: [PATCH v2] bus: mhi: host: pci: Disable runtime PM for QDU100

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Message-ID: <d567e604-bd24-e6bd-92c8-932e0f18dc1f@quicinc.com>
Date: Fri, 18 Apr 2025 18:30:58 +0530
From: Krishna Chaitanya Chundru <quic_krichai@...cinc.com>
To: Vivek Pernamitta <quic_vpernami@...cinc.com>,
        Manivannan Sadhasivam
	<manivannan.sadhasivam@...aro.org>
CC: <mhi@...ts.linux.dev>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] bus: mhi: host: pci: Disable runtime PM for QDU100



On 4/18/2025 5:20 PM, Vivek Pernamitta wrote:
> The QDU100 device does not support the MHI M3 state, necessitating the
> disabling of runtime PM for this device. It is essential to disable
> runtime PM if the device does not support Low Power Mode (LPM).
> 
> Signed-off-by: Vivek Pernamitta <quic_vpernami@...cinc.com>
Reviewed-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> ---
> Changes in v2:
> - Updated device from getting runtime suspended by avoid skipping autosuspend.
> - Updated commit message.
> - Link to v1: https://lore.kernel.org/r/20250414-vdev_next-20250411_pm_disable-v1-1-e963677636ca@quicinc.com
> ---
>   drivers/bus/mhi/host/pci_generic.c | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/bus/mhi/host/pci_generic.c b/drivers/bus/mhi/host/pci_generic.c
> index 03aa887952098661a488650053a357f883d1559b..bec1ca17ad69ac89e2ea9142024fef8bded258b6 100644
> --- a/drivers/bus/mhi/host/pci_generic.c
> +++ b/drivers/bus/mhi/host/pci_generic.c
> @@ -43,6 +43,7 @@
>    * @mru_default: default MRU size for MBIM network packets
>    * @sideband_wake: Devices using dedicated sideband GPIO for wakeup instead
>    *		   of inband wake support (such as sdx24)
> + * @pm_disable: disables runtime PM (optional)
>    */
>   struct mhi_pci_dev_info {
>   	const struct mhi_controller_config *config;
> @@ -54,6 +55,7 @@ struct mhi_pci_dev_info {
>   	unsigned int dma_data_width;
>   	unsigned int mru_default;
>   	bool sideband_wake;
> +	bool pm_disable;
>   };
>   
>   #define MHI_CHANNEL_CONFIG_UL(ch_num, ch_name, el_count, ev_ring) \
> @@ -295,6 +297,7 @@ static const struct mhi_pci_dev_info mhi_qcom_qdu100_info = {
>   	.bar_num = MHI_PCI_DEFAULT_BAR_NUM,
>   	.dma_data_width = 32,
>   	.sideband_wake = false,
> +	.pm_disable = true,
>   };
>   
>   static const struct mhi_channel_config mhi_qcom_sa8775p_channels[] = {
> @@ -1270,8 +1273,11 @@ static int mhi_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>   	/* start health check */
>   	mod_timer(&mhi_pdev->health_check_timer, jiffies + HEALTH_CHECK_PERIOD);
>   
> -	/* Only allow runtime-suspend if PME capable (for wakeup) */
> -	if (pci_pme_capable(pdev, PCI_D3hot)) {
> +	/**
> +	 * Disable Runtime PM if device doesn't support MHI M3 state
> +	 * and Allow runtime-suspend if PME capable (for wakeup)
> +	 */
> +	if (pci_pme_capable(pdev, PCI_D3hot) && !(info->pm_disable)) {
>   		pm_runtime_set_autosuspend_delay(&pdev->dev, 2000);
>   		pm_runtime_use_autosuspend(&pdev->dev);
>   		pm_runtime_mark_last_busy(&pdev->dev);
> 
> ---
> base-commit: 01c6df60d5d4ae00cd5c1648818744838bba7763
> change-id: 20250414-vdev_next-20250411_pm_disable-53d5e1acd45e
> 
> Best regards,