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Message-ID: <53fdf634-ab24-469f-b4d1-5e9a8c9c113d@quicinc.com>
Date: Wed, 29 May 2024 09:09:16 -0700
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Subject: Re: [PATCH] wifi: ath12k: add panic handler
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To: Baochen Qiang <quic_bqiang@quicinc.com>, <ath12k@lists.infradead.org>
CC: <linux-wireless@vger.kernel.org>
References: <20240529021533.10861-1-quic_bqiang@quicinc.com>
From: Jeff Johnson <quic_jjohnson@quicinc.com>
In-Reply-To: <20240529021533.10861-1-quic_bqiang@quicinc.com>
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On 5/28/2024 7:15 PM, Baochen Qiang wrote:
> Currently for ath12k PCI devices, firmware could be running in one of
> several execution environments, e.g., PBL, SBL and mission mode etc. Among
> which PBL is the only stage where PCIe link negotiation could happen. So
> normally firmware runs in PBL in order to be enumerated during system reboot.
> 
> However it might not work in kernel crash scenario: ath12k target is not
> found after warm reboot from kernel crash. This is because when kernel crashes,
> ath12k host does nothing to firmware. And during warm reboot, WLAN power
> is sustained. So firmware is likely to keep running in mission mode throughout
> the bootup process. As a result PCIe link is not established and thus target
> not enumerated.
> 
> So add a handler in panic notification list for ath12k. When kernel crashes,
> this handler gets called and tries to reset target to PBL state. Then PCIe
> link negotiation could happen and target gets enumerated.
> 
> This change applies to all PCI devices including WCN7850 and QCN9274.
> 
> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0-03427-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.15378.4
> 
> Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>