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Message-ID: <66edb53d-edd8-4bdc-8573-2f7cf2f31c53@quicinc.com>
Date:   Mon, 20 Nov 2023 16:39:16 -0800
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH 5/7] wifi: ath12k: add support one MSI vector
Content-Language: en-US
To:     Kang Yang <quic_kangyang@quicinc.com>, <ath12k@lists.infradead.org>
CC:     <linux-wireless@vger.kernel.org>
References: <20231120101543.4369-1-quic_kangyang@quicinc.com>
 <20231120101543.4369-6-quic_kangyang@quicinc.com>
From:   Jeff Johnson <quic_jjohnson@quicinc.com>
In-Reply-To: <20231120101543.4369-6-quic_kangyang@quicinc.com>
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Precedence: bulk

On 11/20/2023 2:15 AM, Kang Yang wrote:
> On some platforms it's not possible to allocate 32 MSI vectors for
> various reasons, maybe kernel configuration, VT-d disabled, buggy BIOS
> etc. So ath12k was not able to use WCN7850 PCI devices on those
> platforms. Add support for one MSI vector to solve that.
> 
> In case of one MSI vector, interrupt migration needs to be disabled.
> This is because when interrupt migration happens, the msi_data may
> change. However, msi_data is already programmed to rings during initial
> phase and ath12k has no way to know that msi_data is changed during run
> time and reprogram again.
> 
> In case of one MSI vector, MHI subsystem should not use IRQF_NO_SUSPEND
> as WCN7850 doesn't set this flag too. Ath12k doesn't need to leave IRQ
> enabled in suspend state.
> 
> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0-03427-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.15378.4
> 
> Signed-off-by: Kang Yang <quic_kangyang@quicinc.com>
> ---
>  drivers/net/wireless/ath/ath12k/mhi.c | 16 +++++++--
>  drivers/net/wireless/ath/ath12k/pci.c | 51 ++++++++++++++++++++-------
>  2 files changed, 52 insertions(+), 15 deletions(-)

...

> diff --git a/drivers/net/wireless/ath/ath12k/pci.c b/drivers/net/wireless/ath/ath12k/pci.c
> index 3bb2d622dc52..4484bac18f4e 100644
> --- a/drivers/net/wireless/ath/ath12k/pci.c
> +++ b/drivers/net/wireless/ath/ath12k/pci.c

...

> @@ -713,18 +731,26 @@ static int ath12k_pci_msi_alloc(struct ath12k_pci *ab_pci)
>  					    msi_config->total_vectors,
>  					    msi_config->total_vectors,
>  					    PCI_IRQ_MSI);
> -	if (num_vectors != msi_config->total_vectors) {
> -		ath12k_err(ab, "failed to get %d MSI vectors, only %d available",
> -			   msi_config->total_vectors, num_vectors);
>  
> -		if (num_vectors >= 0)
> -			return -EINVAL;
> -		else
> -			return num_vectors;
> -	} else {
> +	if (num_vectors == msi_config->total_vectors) {
>  		set_bit(ATH12K_PCI_FLAG_MULTI_MSI_VECTORS, &ab_pci->flags);
>  		ab_pci->irq_flags = IRQF_SHARED;
> +	} else {
> +		num_vectors = pci_alloc_irq_vectors(ab_pci->pdev,
> +						    1,
> +						    1,
> +						    PCI_IRQ_MSI);
> +		if (num_vectors < 0) {
> +			ret = -EINVAL;
> +			goto reset_msi_config;
> +		}
> +		clear_bit(ATH12K_PCI_FLAG_MULTI_MSI_VECTORS, &ab_pci->flags);
> +		ab_pci->msi_config = &msi_config_one_msi;
> +		ab_pci->irq_flags = IRQF_SHARED | IRQF_NOBALANCING;
> +		ath12k_dbg(ab, ATH12K_DBG_PCI, "request MSI one vector\n");
> +

ath12k-check is flagging this:
drivers/net/wireless/ath/ath12k/pci.c:761: Blank lines aren't necessary
before a close brace '}'
<
>  	}
> +	ath12k_info(ab, "MSI vectors: %d\n", num_vectors);
>  
>  	ath12k_pci_msi_disable(ab_pci);
>