netdev - Re: [PATCH v2 net] qede: fix firmware halt over suspend and resume

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Date: Thu, 10 Aug 2023 17:47:18 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Manish Chopra <manishc@...vell.com>
Cc: <netdev@...r.kernel.org>, <aelior@...vell.com>, <palok@...vell.com>,
 <njavali@...vell.com>, <skashyap@...vell.com>, <jmeneghi@...hat.com>,
 <yuval.mintz@...gic.com>, <skalluru@...vell.com>, <pabeni@...hat.com>,
 <edumazet@...gle.com>, <horms@...nel.org>, David Miller
 <davem@...emloft.net>
Subject: Re: [PATCH v2 net] qede: fix firmware halt over suspend and resume

On Wed, 9 Aug 2023 19:13:39 +0530 Manish Chopra wrote:
> While performing certain power-off sequences, PCI drivers are
> called to suspend and resume their underlying devices through
> PCI PM (power management) interface. However this NIC hardware
> does not support PCI PM suspend/resume operations so system wide
> suspend/resume leads to bad MFW (management firmware) state which
> causes various follow-up errors in driver when communicating with
> the device/firmware afterwards.

Does the FW end up recovering? That could still be preferable
to rejecting suspend altogether. Reject is a big hammer,
I'm a bit worried it will cause a regression in stable.

> To fix this driver implements PCI PM suspend handler to indicate
> unsupported operation to the PCI subsystem explicitly, thus avoiding
> system to go into suspended/standby mode.
> 
> Fixes: 2950219d87b0 ("qede: Add basic network device support")
> Cc: David Miller <davem@...emloft.net>
> Signed-off-by: Manish Chopra <manishc@...vell.com>
> Signed-off-by: Alok Prasad <palok@...vell.com>
> ---
> V1->V2:
> * Replace SIMPLE_DEV_PM_OPS with DEFINE_SIMPLE_DEV_PM_OPS
> ---
>  drivers/net/ethernet/qlogic/qede/qede_main.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/net/ethernet/qlogic/qede/qede_main.c b/drivers/net/ethernet/qlogic/qede/qede_main.c
> index d57e52a97f85..18ae7af1764c 100644
> --- a/drivers/net/ethernet/qlogic/qede/qede_main.c
> +++ b/drivers/net/ethernet/qlogic/qede/qede_main.c
> @@ -177,6 +177,18 @@ static int qede_sriov_configure(struct pci_dev *pdev, int num_vfs_param)
>  }
>  #endif
>  
> +static int __maybe_unused qede_suspend(struct device *dev)
> +{
> +	if (!dev)
> +		return -ENODEV;

Can dev really be NULL here? That wouldn't make sense, what's the
driver supposed to do in such case?
-- 
pw-bot: cr