Re: [PATCH v2 3/9] PCI/ASPM: Use RMW accessors for changing LNKCTL

From: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
To: Lukas Wunner <lukas@wunner.de>
Cc: linux-pci@vger.kernel.org, "Bjorn Helgaas" <bhelgaas@google.com>,
	"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
	"Rob Herring" <robh@kernel.org>,
	"Krzysztof Wilczy??ski" <kw@linux.com>,
	"Emmanuel Grumbach" <emmanuel.grumbach@intel.com>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	"Heiner Kallweit" <hkallweit1@gmail.com>,
	"Stefan Mätje" <stefan.maetje@esd.eu>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Jesse Barnes" <jbarnes@virtuousgeek.org>,
	"Matthew Garrett" <mjg59@srcf.ucam.org>,
	"Shaohua Li" <shaohua.li@intel.com>,
	"Thomas Renninger" <trenn@suse.de>,
	"Greg Kroah-Hartman" <gregkh@suse.de>,
	LKML <linux-kernel@vger.kernel.org>,
	"Dean Luick" <dean.luick@cornelisnetworks.com>,
	stable@vger.kernel.org
Subject: Re: [PATCH v2 3/9] PCI/ASPM: Use RMW accessors for changing LNKCTL
Date: Mon, 19 Jun 2023 17:45:06 +0300 (EEST)	[thread overview]
Message-ID: <f6397fe9-bc77-fe1f-b941-f8aac91bea65@linux.intel.com> (raw)
In-Reply-To: <20230616191056.GA30821@wunner.de>

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On Fri, 16 Jun 2023, Lukas Wunner wrote:

> On Wed, May 17, 2023 at 01:52:29PM +0300, Ilpo Järvinen wrote:
> > Don't assume that the device is fully under the control of ASPM and use
> > RMW capability accessors which do proper locking to avoid losing
> > concurrent updates to the register values.
> > 
> > If configuration fails in pcie_aspm_configure_common_clock(), the
> > function attempts to restore the old PCI_EXP_LNKCTL_CCC settings. Store
> > only the old PCI_EXP_LNKCTL_CCC bit for the relevant devices rather
> > than the content of the whole LNKCTL registers. It aligns better with
> > how pcie_lnkctl_clear_and_set() expects its parameter and makes the
> > code more obvious to understand.
> [...]
> > @@ -224,17 +223,14 @@ static bool pcie_retrain_link(struct pcie_link_state *link)
> >  	if (!pcie_wait_for_retrain(parent))
> >  		return false;
> >  
> > -	pcie_capability_read_word(parent, PCI_EXP_LNKCTL, &reg16);
> > -	reg16 |= PCI_EXP_LNKCTL_RL;
> > -	pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
> > +	pcie_capability_set_word(parent, PCI_EXP_LNKCTL, PCI_EXP_LNKCTL_RL);
> >  	if (parent->clear_retrain_link) {
> 
> This and several other RMW operations in drivers/pci/pcie/aspm.c
> are touched by commit b1689799772a ("PCI/ASPM: Use distinct local
> vars in pcie_retrain_link()") which got applied to pci/enumeration
> this week:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?h=enumeration&id=b1689799772a6f4180f918b0ff66e264a3db9796
> 
> As a result the $SUBJECT_PATCH no longer applies cleanly and needs
> to be respun.

Okay but I'm a bit lost which commit/head in pci repo I should now base 
this series because there's a conflict between pci/aspm and 
pci/enumeration which is not resolved in the repo because pci/enumeration 
hasn't advanced into pci/next yet. Any suggestion?

-- 
 i.