Received-SPF: pass (google.com: best guess record for domain of linux-wireless-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 5293A60F78
From:   Kalle Valo <kvalo@codeaurora.org>
To:     Lorenzo Bianconi <lorenzo@kernel.org>
Cc:     linux-wireless@vger.kernel.org, nbd@nbd.name, sgruszka@redhat.com,
        lorenzo.bianconi@redhat.com, oleksandr@natalenko.name,
        netdev@vger.kernel.org
Subject: Re: [PATCH wireless-drivers 1/2] mt76: mt76x2e: disable pcie_aspm by default
References: <cover.1571868221.git.lorenzo@kernel.org>
        <fec60f066bab1936d58b2e69bae3f20e645d1304.1571868221.git.lorenzo@kernel.org>
Date:   Thu, 24 Oct 2019 08:03:16 +0300
In-Reply-To: <fec60f066bab1936d58b2e69bae3f20e645d1304.1571868221.git.lorenzo@kernel.org>
        (Lorenzo Bianconi's message of "Thu, 24 Oct 2019 00:23:15 +0200")
Message-ID: <87eez2u44r.fsf@kamboji.qca.qualcomm.com>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

Lorenzo Bianconi <lorenzo@kernel.org> writes:

> On same device (e.g. U7612E-H1) PCIE_ASPM causes continuous mcu hangs and
> instability and so let's disable PCIE_ASPM by default. This patch has
> been successfully tested on U7612E-H1 mini-pice card
>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>

[...]

> +void mt76_mmio_disable_aspm(struct pci_dev *pdev)
> +{
> +	struct pci_dev *parent = pdev->bus->self;
> +	u16 aspm_conf, parent_aspm_conf = 0;
> +
> +	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &aspm_conf);
> +	aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
> +	if (parent) {
> +		pcie_capability_read_word(parent, PCI_EXP_LNKCTL,
> +					  &parent_aspm_conf);
> +		parent_aspm_conf &= PCI_EXP_LNKCTL_ASPMC;
> +	}
> +
> +	if (!aspm_conf && (!parent || !parent_aspm_conf)) {
> +		/* aspm already disabled */
> +		return;
> +	}
> +
> +	dev_info(&pdev->dev, "disabling ASPM %s %s\n",
> +		 (aspm_conf & PCI_EXP_LNKCTL_ASPM_L0S) ? "L0s" : "",
> +		 (aspm_conf & PCI_EXP_LNKCTL_ASPM_L1) ? "L1" : "");
> +
> +#ifdef CONFIG_PCIEASPM
> +	pci_disable_link_state(pdev, aspm_conf);
> +
> +	/* Double-check ASPM control.  If not disabled by the above, the
> +	 * BIOS is preventing that from happening (or CONFIG_PCIEASPM is
> +	 * not enabled); override by writing PCI config space directly.
> +	 */
> +	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &aspm_conf);
> +	if (!(aspm_conf & PCI_EXP_LNKCTL_ASPMC))
> +		return;
> +#endif /* CONFIG_PCIEASPM */

A minor comment, but 'if IS_ENABLED(CONFIG_PCIEASPM)' is preferred over
#ifdef. Better compiler coverage and so on.

-- 
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches