Re: [PATCH] PCI: Align MPS to upstream bridge for SAFE and PERFORMANCE mode

[Tyler Hicks <code@tyhicks.com>]

On 2022-09-14 09:41:05, Tyler Hicks wrote:
> On 2022-08-26 10:49:39, Tyler Hicks wrote:
> > On 2022-06-10 23:01:31, Zhiqiang Hou wrote:
> > > From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > > 
> > > The commit 27d868b5e6cf ("PCI: Set MPS to match upstream bridge")
> > > made the device's MPS matches upstream bridge for PCIE_BUS_DEFAULT
> > > mode, so that it's more likely that a hot-added device will work in
> > > a system with an optimized MPS configuration.
> > > 
> > > Obviously, the Linux itself optimizes the MPS settings in the
> > > PCIE_BUS_SAFE and PCIE_BUS_PERFORMANCE mode, so let's do this also
> > > for these modes.
> > > 
> > > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
> > > ---
> > 
> > Hi Bjorn - We have some interest in this patch and I am hoping it can be
> > considered in preparation for v6.1. I took a look at it and it makes
> > sense to me but I'm not an expert in this area. Thanks!
> 
> Ping. Do you expect to get any free cycles to review this in prep for
> v6.1?

Ping now that you've got the v6.1 PR out for the PCI subsystem. Thanks. 

> 
> Tyler
> 
> > 
> > Tyler
> > 
> > >  drivers/pci/probe.c | 6 ++++--
> > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> > > index 17a969942d37..2c5a1aefd9cb 100644
> > > --- a/drivers/pci/probe.c
> > > +++ b/drivers/pci/probe.c
> > > @@ -2034,7 +2034,9 @@ static void pci_configure_mps(struct pci_dev *dev)
> > >  	 * Fancier MPS configuration is done later by
> > >  	 * pcie_bus_configure_settings()
> > >  	 */
> > > -	if (pcie_bus_config != PCIE_BUS_DEFAULT)
> > > +	if (pcie_bus_config != PCIE_BUS_DEFAULT &&
> > > +	    pcie_bus_config != PCIE_BUS_SAFE &&
> > > +	    pcie_bus_config != PCIE_BUS_PERFORMANCE)
> > >  		return;
> > >  
> > >  	mpss = 128 << dev->pcie_mpss;
> > > @@ -2047,7 +2049,7 @@ static void pci_configure_mps(struct pci_dev *dev)
> > >  
> > >  	rc = pcie_set_mps(dev, p_mps);
> > >  	if (rc) {
> > > -		pci_warn(dev, "can't set Max Payload Size to %d; if necessary, use \"pci=pcie_bus_safe\" and report a bug\n",
> > > +		pci_warn(dev, "can't set Max Payload Size to %d; if necessary, use \"pci=pcie_bus_peer2peer\" and report a bug\n",
> > >  			 p_mps);
> > >  		return;
> > >  	}
> > > -- 
> > > 2.17.1
> > >