Re: [PATCH 1/3] PCI/ASPM: Disable ASPM_STATE_L1 only when class driver disables L1 ASPM

[Ajay Agarwal <ajayagarwal@google.com>]

On Mon, May 01, 2023 at 12:21:14PM -0500, Bjorn Helgaas wrote:
> On Tue, Apr 11, 2023 at 04:40:32PM +0530, Ajay Agarwal wrote:
> > Currently the aspm driver sets ASPM_STATE_L1 as well as
> > ASPM_STATE_L1SS bits when the class driver disables L1.
> 
> I would have said just "driver" -- do you mean something different by
> using "class driver"?  The callers I see are garden-variety drivers
> for individual devices like hci_bcm4377, xillybus_pcie, e1000e, jme,
> etc.
No, I do not mean anything different by "class driver". I just wanted
to name the caller drivers of the ASPM APIs as something other than
just "driver". Do you want me to change this to "driver" ?
> 
> > pcie_config_aspm_link takes care that L1ss ASPM is not enabled
> > if L1 is disabled. ASPM_STATE_L1SS bits do not need to be
> > explicitly set. The sysfs node store() function, which also
> > modifies the aspm_disable value, does not set these bits either
> > when only L1 ASPM is disabled by the user.
> 
> Right.  It'd be nice to combine __pci_disable_link_state() and
> aspm_attr_store_common() so they use the same logic for this, but
> that's not really trivial to do.
> 
Ack.
> > Disable ASPM_STATE_L1 only when class driver disables L1 ASPM.
> 
> So IIUC, this is a cleanup and should not fix any actual function
> bugs, right?  If it *does* fix a bug, we should add a Fixes: tag and a
> description of the bug.
> 
Yes, this is just a cleanup.
> > Signed-off-by: Ajay Agarwal <ajayagarwal@google.com>
> > ---
> >  drivers/pci/pcie/aspm.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> > index 66d7514ca111..5765b226102a 100644
> > --- a/drivers/pci/pcie/aspm.c
> > +++ b/drivers/pci/pcie/aspm.c
> > @@ -1095,8 +1095,7 @@ static int __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)
> >  	if (state & PCIE_LINK_STATE_L0S)
> >  		link->aspm_disable |= ASPM_STATE_L0S;
> >  	if (state & PCIE_LINK_STATE_L1)
> > -		/* L1 PM substates require L1 */
> > -		link->aspm_disable |= ASPM_STATE_L1 | ASPM_STATE_L1SS;
> > +		link->aspm_disable |= ASPM_STATE_L1;
> >  	if (state & PCIE_LINK_STATE_L1_1)
> >  		link->aspm_disable |= ASPM_STATE_L1_1;
> >  	if (state & PCIE_LINK_STATE_L1_2)
> > -- 
> > 2.40.0.577.gac1e443424-goog
> >