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

[Tyler Hicks <tyhicks@linux.microsoft.com>]

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?

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
> >