ZQ, On Tue, Jan 29, 2019 at 1:41 PM Z.q. Hou <zhiqiang.hou@xxxxxxx> wrote: > > From: Hou Zhiqiang <Zhiqiang.Hou@xxxxxxx> > > When LX2 PCIe controller is sending multiple split completions and > ACK latency expires indicating that ACK should be send at priority. > But because of large number of split completions and FC update DLLP, > the controller does not give priority to ACK transmission. This > results into ACK latency timer timeout error at the link partner and > the pending TLPs are replayed by the link partner again. > > Workaround: > 1. Reduce the ACK latency timeout value to a very small value. > 2. Restrict the number of completions from the LX2 PCIe controller > to 1, by changing the Max Read Request Size (MRRS) of link partner > to the same value as Max Packet size (MPS). > > This patch implemented part 1, the part 2 can be set by kernel parameter > 'pci=pcie_bus_perf' > > This ERRATA is only for LX2160A Rev1.0, and it will be fixed > in Rev2.0. > > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@xxxxxxx> > --- > V3: > - Integrated without change from http://patchwork.ozlabs.org/patch/1006796/ > > .../pci/controller/mobiveil/pci-layerscape-gen4.c | 15 +++++++++++++++ > drivers/pci/controller/mobiveil/pcie-mobiveil.h | 4 ++++ > 2 files changed, 19 insertions(+) > > diff --git a/drivers/pci/controller/mobiveil/pci-layerscape-gen4.c b/drivers/pci/controller/mobiveil/pci-layerscape-gen4.c > index d2c5dbbd5e3c..20ce146788ca 100644 > --- a/drivers/pci/controller/mobiveil/pci-layerscape-gen4.c > +++ b/drivers/pci/controller/mobiveil/pci-layerscape-gen4.c > @@ -82,12 +82,27 @@ static bool ls_pcie_g4_is_bridge(struct ls_pcie_g4 *pcie) > return header_type == PCI_HEADER_TYPE_BRIDGE; > } > > +static void workaround_A011451(struct ls_pcie_g4 *pcie) > +{ > + struct mobiveil_pcie *mv_pci = pcie->pci; > + u32 val; > + > + /* Set ACK latency timeout */ > + val = csr_readl(mv_pci, GPEX_ACK_REPLAY_TO); > + val &= ~(ACK_LAT_TO_VAL_MASK << ACK_LAT_TO_VAL_SHIFT); > + val |= (4 << ACK_LAT_TO_VAL_SHIFT); > + csr_writel(mv_pci, val, GPEX_ACK_REPLAY_TO); > +} > + > static int ls_pcie_g4_host_init(struct mobiveil_pcie *pci) > { > struct ls_pcie_g4 *pcie = to_ls_pcie_g4(pci); > > pcie->rev = csr_readb(pci, PCI_REVISION_ID); > > + if (pcie->rev == REV_1_0) > + workaround_A011451(pcie); > + > return 0; > } > > diff --git a/drivers/pci/controller/mobiveil/pcie-mobiveil.h b/drivers/pci/controller/mobiveil/pcie-mobiveil.h > index ab43de5e4b2b..f0e2e4ae09b5 100644 > --- a/drivers/pci/controller/mobiveil/pcie-mobiveil.h > +++ b/drivers/pci/controller/mobiveil/pcie-mobiveil.h > @@ -85,6 +85,10 @@ > #define PAB_AXI_AMAP_PEX_WIN_H(win) PAB_REG_ADDR(0x0bac, win) > #define PAB_INTP_AXI_PIO_CLASS 0x474 > > +#define GPEX_ACK_REPLAY_TO 0x438 > +#define ACK_LAT_TO_VAL_MASK 0x1fff > +#define ACK_LAT_TO_VAL_SHIFT 0 > + > #define PAB_PEX_AMAP_CTRL(win) PAB_REG_ADDR(0x4ba0, win) > #define AMAP_CTRL_EN_SHIFT 0 > #define AMAP_CTRL_TYPE_SHIFT 1 > -- > 2.17.1 > again, can we avoid errata number on patch title and have a brief title instead?
