> -----Original Message----- > From: Bjorn Helgaas [mailto:helgaas@xxxxxxxxxx] > Sent: Tuesday, April 03, 2018 7:06 AM > To: Jacob Keller <jacob.keller@xxxxxxxxx> > Cc: Tal Gilboa <talgi@xxxxxxxxxxxx>; Tariq Toukan <tariqt@xxxxxxxxxxxx>; > Keller, Jacob E <jacob.e.keller@xxxxxxxxx>; Ariel Elior <ariel.elior@xxxxxxxxxx>; > Ganesh Goudar <ganeshgr@xxxxxxxxxxx>; Kirsher, Jeffrey T > <jeffrey.t.kirsher@xxxxxxxxx>; everest-linux-l2@xxxxxxxxxx; intel-wired- > lan@xxxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linux-pci@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v5 03/14] PCI: Add pcie_bandwidth_capable() to compute > max supported link bandwidth > > On Mon, Apr 02, 2018 at 05:30:54PM -0700, Jacob Keller wrote: > > On Mon, Apr 2, 2018 at 7:05 AM, Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > > +/* PCIe speed to Mb/s reduced by encoding overhead */ > > > +#define PCIE_SPEED2MBS_ENC(speed) \ > > > + ((speed) == PCIE_SPEED_16_0GT ? (16000*(128/130)) : \ > > > + (speed) == PCIE_SPEED_8_0GT ? (8000*(128/130)) : \ > > > + (speed) == PCIE_SPEED_5_0GT ? (5000*(8/10)) : \ > > > + (speed) == PCIE_SPEED_2_5GT ? (2500*(8/10)) : \ > > > + 0) > > > + > > > > Should this be "(speed * x ) / y" instead? wouldn't they calculate > > 128/130 and truncate that to zero before multiplying by the speed? Or > > are compilers smart enough to do this the other way to avoid the > > losses? > > Yep, thanks for saving me yet more embarrassment. That's what patch review is for :D Thanks, Jake
