linux-kernel - Re: [net-next v2] net: wwan: t7xx: reset device if suspend fails

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Message-ID: <11e25027-6987-4c88-ac06-c1ba60c0d113@gmail.com>
Date: Tue, 29 Oct 2024 02:58:16 +0200
From: Sergey Ryazanov <ryazanov.s.a@...il.com>
To: Jinjian Song <jinjian.song@...ocom.com>,
 chandrashekar.devegowda@...el.com, chiranjeevi.rapolu@...ux.intel.com,
 haijun.liu@...iatek.com, m.chetan.kumar@...ux.intel.com,
 ricardo.martinez@...ux.intel.com, loic.poulain@...aro.org,
 johannes@...solutions.net, davem@...emloft.net, edumazet@...gle.com,
 kuba@...nel.org, pabeni@...hat.com
Cc: linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
 linux-doc@...r.kernel.org, angelogioacchino.delregno@...labora.com,
 linux-arm-kernel@...ts.infradead.org, matthias.bgg@...il.com,
 corbet@....net, linux-mediatek@...ts.infradead.org, helgaas@...nel.org,
 danielwinkler@...gle.com, korneld@...gle.com
Subject: Re: [net-next v2] net: wwan: t7xx: reset device if suspend fails

Hello Jinjian,

On 22.10.2024 11:43, Jinjian Song wrote:
> If driver fails to set the device to suspend, it means that the
> device is abnormal. In this case, reset the device to recover
> when PCIe device is offline.

Is it a reproducible or a speculative issue? Does the fix recover modem 
from a problematic state?

Anyway we need someone more familiar with this hardware (Intel or 
MediaTek engineer) to Ack the change to make sure we are not going to 
put a system in a more complicated state.

> Signed-off-by: Jinjian Song <jinjian.song@...ocom.com>
> ---
> V2:
>   * Add judgment, reset when device is offline
> ---
>   drivers/net/wwan/t7xx/t7xx_pci.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/wwan/t7xx/t7xx_pci.c b/drivers/net/wwan/t7xx/t7xx_pci.c
> index e556e5bd49ab..4f89a353588b 100644
> --- a/drivers/net/wwan/t7xx/t7xx_pci.c
> +++ b/drivers/net/wwan/t7xx/t7xx_pci.c
> @@ -427,6 +427,10 @@ static int __t7xx_pci_pm_suspend(struct pci_dev *pdev)
>   	iowrite32(T7XX_L1_BIT(0), IREG_BASE(t7xx_dev) + ENABLE_ASPM_LOWPWR);
>   	atomic_set(&t7xx_dev->md_pm_state, MTK_PM_RESUMED);
>   	t7xx_pcie_mac_set_int(t7xx_dev, SAP_RGU_INT);
> +	if (pci_channel_offline(pdev)) {
> +		dev_err(&pdev->dev, "Device offline, reset to recover\n");
> +		t7xx_reset_device(t7xx_dev, PLDR);
> +	}
>   	return ret;
>   }

--
Sergey