linux-kernel - Re: [PATCH v3 04/11] PCI/ASPM: Clear aspm_disable as part of __pci_enable_link

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Message-ID: <649c2bb2-d9a3-66ce-8bc5-2735195aaa5e@linux.intel.com>
Date: Mon, 19 May 2025 16:21:32 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
cc: Bjorn Helgaas <bhelgaas@...gle.com>, Jingoo Han <jingoohan1@...il.com>, 
    Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
    Lorenzo Pieralisi <lpieralisi@...nel.org>, 
    Krzysztof Wilczyński <kw@...ux.com>, 
    Rob Herring <robh@...nel.org>, Johannes Berg <johannes@...solutions.net>, 
    Jeff Johnson <jjohnson@...nel.org>, Bartosz Golaszewski <brgl@...ev.pl>, 
    linux-pci@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>, 
    linux-arm-msm@...r.kernel.org, mhi@...ts.linux.dev, 
    linux-wireless@...r.kernel.org, ath11k@...ts.infradead.org, 
    qiang.yu@....qualcomm.com, quic_vbadigan@...cinc.com, 
    quic_vpernami@...cinc.com, quic_mrana@...cinc.com, 
    Jeff Johnson <jeff.johnson@....qualcomm.com>
Subject: Re: [PATCH v3 04/11] PCI/ASPM: Clear aspm_disable as part of
 __pci_enable_link_state()

On Mon, 19 May 2025, Krishna Chaitanya Chundru wrote:

> If a driver wants to enable ASPM back after disabling ASPM for some
> usecase, it is not being enabled properly because of the aspm_disable
> flag is not getting cleared. This flag is being properly when aspm
> is controlled by sysfs.

This sentence has broken grammar/is missing something?

aspm -> ASPM

> 
> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> ---
>  drivers/pci/pcie/aspm.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index 94324fc0d3e650cd3ca2c0bb8c1895ca7e647b9d..0f858ef86111b43328bc7db01e6493ce67178458 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -1453,6 +1453,7 @@ static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked)
>  		down_read(&pci_bus_sem);
>  	mutex_lock(&aspm_lock);
>  	link->aspm_default = pci_calc_aspm_enable_mask(state);
> +	link->aspm_disable &= ~state;
>  	pcie_config_aspm_link(link, policy_to_aspm_state(link));
>  
>  	link->clkpm_default = (state & PCIE_LINK_STATE_CLKPM) ? 1 : 0;

I disagree with this change.

The problem currently with ASPM driver is that pci_disable_link_state() 
and pci_enable_link_state() are not symmetric pairs despite their 
misleading names. pci_enable_link_state() should be renamed to 
pci_set_default_link_state() and if the symmetric pair is needed for 
pci_disable_link_state(), it would have to be added separately.

I've some (rotting) patches which try to do that, in case you want to try 
to solve this inconsistency in the ASPM driver (I can send them to you)?

-- 
 i.