linux-kernel - Re: [PATCH v3] bus: mhi: host: pci: Disable runtime PM for QDU100

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Message-ID: <ciwwfmadzgpzaie5isrmpzd7s373bgyk27hh5fjaqy6blqa4qo@ar7cdrv3uuxy>
Date: Fri, 25 Apr 2025 12:38:34 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Vivek Pernamitta <quic_vpernami@...cinc.com>
Cc: mhi@...ts.linux.dev, linux-arm-msm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Subject: Re: [PATCH v3] bus: mhi: host: pci: Disable runtime PM for QDU100

On Fri, Apr 18, 2025 at 07:18:18PM +0530, 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).

LPM is not very clear here. Please just use M3.

> 
> Signed-off-by: Vivek Pernamitta <quic_vpernami@...cinc.com>
> Reviewed-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> ---
> Changes in v3:
> - updated variable to no_m3 from pm_disable 
> - Link to v2: https://lore.kernel.org/r/20250418-vdev_next-20250411_pm_disable-v2-1-27dd8d433f3b@quicinc.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..df80f3f62278d2cf96066c04926ce1ce58700d1b 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)
> + * @no_m3: M3 is disabled (optional)

Remove 'optional'. It is an opt-in value.

>   */
>  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 no_m3;
>  };
>  
>  #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,
> +	.no_m3 = 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)

"Only allow runtime suspend if both PME from D3Hot and M3 are supported"

- Mani

-- 
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