RE: [PATCHv4 26/28] PCI: mobiveil: ls_pcie_g4: add Workaround for A-011451

[Z.q. Hou]

Hi All,

Please ignore this patch, rev1.0 will not be production.

Thanks,
Zhiqiang


> -----Original Message-----
> From: Z.q. Hou
> Sent: 2019年3月11日 17:34
> To: linux-pci@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> bhelgaas@xxxxxxxxxx; robh+dt@xxxxxxxxxx; mark.rutland@xxxxxxx;
> l.subrahmanya@xxxxxxxxxxxxxx; shawnguo@xxxxxxxxxx; Leo Li
> <leoyang.li@xxxxxxx>; lorenzo.pieralisi@xxxxxxx;
> catalin.marinas@xxxxxxx; will.deacon@xxxxxxx
> Cc: Mingkai Hu <mingkai.hu@xxxxxxx>; M.h. Lian
> <minghuan.lian@xxxxxxx>; Xiaowei Bao <xiaowei.bao@xxxxxxx>; Z.q. Hou
> <zhiqiang.hou@xxxxxxx>
> Subject: [PATCHv4 26/28] PCI: mobiveil: ls_pcie_g4: add Workaround for
> A-011451
> 
> 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>
> ---
> V4:
>  - no change
> 
>  .../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