Re: iMX6q PCIe phy link never came up on kernel v4.4.x

[Roberto Fichera <kernel@tekno-soft.it>]

On 03/03/2016 10:39 AM, Richard Zhu wrote:

Hi Richard,

> [Zhu hongxing] The registers configured during the initialization.
> Regarding to the current situation at your side, the pcie link is up in uboot, but is down in kernel.
> So, you can compare the dump of the register configured during the pcie initialization between uboot and kernel.

Here is the register status before to start LTSSM under uboot

...
I2C:   ready
DRAM:  2 GiB
MMC:   FSL_SDHC: 0, FSL_SDHC: 1
>>> GPR[1] (0x020e0004): 0x48611005
>>> GPR[5] (0x020e0014): 0x00000000
>>> GPR[8] (0x020e0020): 0xfffd4000
>>> GPR[12] (0x020e0030): 0x0f004090
>>> GPC_BASE_ADDR + 0 (0x020dc000): 0x00100000
>>> MX6_DBI_ADDR + 0x7c (0x01ffc07c): 0x0011cc11
DEBUG_R0: 0x036e2b11, DEBUG_R1: 0x08000410
  LTSSM current state: 0x11 (S_L0)
  PIPE transmit K indication: 0
  PIPE Transmit data: 0x6e2b
  Receiver is receiving logical idle: yes

but the funny thing is under kernel, maybe related to some clock setting? see below

[    0.235456] PCI host bridge /soc/pcie@0x01000000 ranges:
[    0.235475]   No bus range found for /soc/pcie@0x01000000, using [bus 00-ff]
[    0.235527]   err 0x01f00000..0x01f7ffff -> 0x01f00000
[    0.235577]    IO 0x01f80000..0x01f8ffff -> 0x00000000
[    0.235659]   MEM 0x01000000..0x01efffff -> 0x01000000
[    0.377644] imx6q-pcie 1ffc000.pcie: >>> GPR[1] (0x00000004): 0x00000000
[    0.377666] imx6q-pcie 1ffc000.pcie: >>> GPR[5] (0x00000014): 0x00000000
[    0.377684] imx6q-pcie 1ffc000.pcie: >>> GPR[8] (0x00000020): 0x00000000
[    0.377701] imx6q-pcie 1ffc000.pcie: >>> GPR[12] (0x00000030): 0x00000000
[    0.377717] imx6q-pcie 1ffc000.pcie: >>> PCIE_RC_LCR (0xf08f007c): 0x0011cc11
[    0.586532] imx6q-pcie 1ffc000.pcie: phy link never came up
[    0.586551] imx6q-pcie 1ffc000.pcie: LTSSM current state: 0x3 (S_POLL_COMPLIANCE)
[    0.586566] imx6q-pcie 1ffc000.pcie: PIPE transmit K indication: 1
[    0.586579] imx6q-pcie 1ffc000.pcie: PIPE Transmit data: 0xb5bc
[    0.586592] imx6q-pcie 1ffc000.pcie: Receiver is receiving logical idle: no

The code I've used to dump the register is using regmap_read(),

#define IMX6_DUMP_REGISTER(__map, __reg, __name) \
  do {\
    uint32_t val;\
    val = regmap_read(__map, __reg, &val);\
    dev_err(pp->dev, ">>> " __name " (0x%08p): 0x%08x\n", __reg, val);\
  } while(0)

#define IMX6_DUMP_REGISTER2(__reg, __name) \
  do {\
    uint32_t val;\
    val = readl(__reg);\
    dev_err(pp->dev, ">>> " __name " (0x%08p): 0x%08x\n", __reg, val);\
  } while(0)


static void imx6_pcie_dump_registers(struct pcie_port *pp)
{
    struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);

        IMX6_DUMP_REGISTER(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1, "GPR[1]");
        IMX6_DUMP_REGISTER(imx6_pcie->iomuxc_gpr, IOMUXC_GPR5, "GPR[5]");
        IMX6_DUMP_REGISTER(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8, "GPR[8]");
        IMX6_DUMP_REGISTER(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12, "GPR[12]");
        IMX6_DUMP_REGISTER2(pp->dbi_base + PCIE_RC_LCR, "PCIE_RC_LCR");
}

Cheers,
Roberto Fichera.