From: Bjorn Helgaas <helgaas@kernel.org>
To: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
Cc: linux-pci@vger.kernel.org, "Bjorn Helgaas" <bhelgaas@google.com>,
"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Rob Herring" <robh@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Emmanuel Grumbach" <emmanuel.grumbach@intel.com>,
"Rafael J . Wysocki" <rafael@kernel.org>,
"Heiner Kallweit" <hkallweit1@gmail.com>,
"Lukas Wunner" <lukas@wunner.de>, "Kalle Valo" <kvalo@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
"Michal Kazior" <michal.kazior@tieto.com>,
"Janusz Dziedzic" <janusz.dziedzic@tieto.com>,
ath10k@lists.infradead.org, linux-wireless@vger.kernel.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
"Dean Luick" <dean.luick@cornelisnetworks.com>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v2 9/9] wifi: ath10k: Use RMW accessors for changing LNKCTL
Date: Wed, 24 May 2023 10:10:54 -0500 [thread overview]
Message-ID: <ZG4o/pYseBklnrTc@bhelgaas> (raw)
In-Reply-To: <20230517105235.29176-10-ilpo.jarvinen@linux.intel.com>
On Wed, May 17, 2023 at 01:52:35PM +0300, Ilpo Järvinen wrote:
> Don't assume that only the driver would be accessing LNKCTL. ASPM
> policy changes can trigger write to LNKCTL outside of driver's control.
>
> Use RMW capability accessors which does proper locking to avoid losing
> concurrent updates to the register value. On restore, clear the ASPMC
> field properly.
>
> Fixes: 76d870ed09ab ("ath10k: enable ASPM")
> Suggested-by: Lukas Wunner <lukas@wunner.de>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> Cc: stable@vger.kernel.org
> ---
> drivers/net/wireless/ath/ath10k/pci.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath10k/pci.c b/drivers/net/wireless/ath/ath10k/pci.c
> index a7f44f6335fb..9275a672f90c 100644
> --- a/drivers/net/wireless/ath/ath10k/pci.c
> +++ b/drivers/net/wireless/ath/ath10k/pci.c
> @@ -1963,8 +1963,9 @@ static int ath10k_pci_hif_start(struct ath10k *ar)
> ath10k_pci_irq_enable(ar);
> ath10k_pci_rx_post(ar);
>
> - pcie_capability_write_word(ar_pci->pdev, PCI_EXP_LNKCTL,
> - ar_pci->link_ctl);
> + pcie_capability_clear_and_set_word(ar_pci->pdev, PCI_EXP_LNKCTL,
> + PCI_EXP_LNKCTL_ASPMC,
> + ar_pci->link_ctl & PCI_EXP_LNKCTL_ASPMC);
>
> return 0;
> }
> @@ -2821,8 +2822,8 @@ static int ath10k_pci_hif_power_up(struct ath10k *ar,
>
> pcie_capability_read_word(ar_pci->pdev, PCI_EXP_LNKCTL,
> &ar_pci->link_ctl);
> - pcie_capability_write_word(ar_pci->pdev, PCI_EXP_LNKCTL,
> - ar_pci->link_ctl & ~PCI_EXP_LNKCTL_ASPMC);
> + pcie_capability_clear_word(ar_pci->pdev, PCI_EXP_LNKCTL,
> + PCI_EXP_LNKCTL_ASPMC);
These ath drivers all have the form:
1) read LNKCTL
2) save LNKCTL value in ->link_ctl
3) write LNKCTL with "->link_ctl & ~PCI_EXP_LNKCTL_ASPMC"
to disable ASPM
4) write LNKCTL with ->link_ctl, presumably to re-enable ASPM
These patches close the hole between 1) and 3) where other LNKCTL
updates could interfere, which is definitely a good thing.
But the hole between 1) and 4) is much bigger and still there. Any
update by the PCI core in that interval would be lost.
Straw-man proposal:
- Change pci_disable_link_state() so it ignores aspm_disabled and
always disables ASPM even if platform firmware hasn't granted
ownership. Maybe this should warn and taint the kernel.
- Change drivers to use pci_disable_link_state() instead of writing
LNKCTL directly.
Bjorn
next prev parent reply other threads:[~2023-05-24 15:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230517105235.29176-1-ilpo.jarvinen@linux.intel.com>
2023-05-17 10:52 ` [PATCH v2 7/9] wifi: ath11k: Use RMW accessors for changing LNKCTL Ilpo Järvinen
2023-05-17 11:04 ` Kalle Valo
2023-05-17 10:52 ` [PATCH v2 8/9] wifi: ath12k: " Ilpo Järvinen
2023-05-17 11:03 ` Kalle Valo
2023-05-17 10:52 ` [PATCH v2 9/9] wifi: ath10k: " Ilpo Järvinen
2023-05-17 11:05 ` Kalle Valo
2023-05-24 15:10 ` Bjorn Helgaas [this message]
2023-05-25 10:11 ` Ilpo Järvinen
2023-05-26 11:48 ` Ilpo Järvinen
2023-05-26 22:26 ` Bjorn Helgaas
2023-05-26 22:20 ` Bjorn Helgaas
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZG4o/pYseBklnrTc@bhelgaas \
--to=helgaas@kernel.org \
--cc=andriy.shevchenko@linux.intel.com \
--cc=ath10k@lists.infradead.org \
--cc=bhelgaas@google.com \
--cc=davem@davemloft.net \
--cc=dean.luick@cornelisnetworks.com \
--cc=edumazet@google.com \
--cc=emmanuel.grumbach@intel.com \
--cc=hkallweit1@gmail.com \
--cc=ilpo.jarvinen@linux.intel.com \
--cc=janusz.dziedzic@tieto.com \
--cc=kuba@kernel.org \
--cc=kvalo@kernel.org \
--cc=kw@linux.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=linux-wireless@vger.kernel.org \
--cc=lorenzo.pieralisi@arm.com \
--cc=lukas@wunner.de \
--cc=michal.kazior@tieto.com \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=rafael@kernel.org \
--cc=robh@kernel.org \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).