[U-Boot] [PATCH] pci: pcie_imx: Fix hang on mx6qp

[Marek Vasut <marex@denx.de>]

On Thursday, October 08, 2015 at 05:49:27 PM, Fabio Estevam wrote:
> PCI driver currently hangs on mx6qp.
> 
> Toggle the reset bit with the appropriate timings to fix the issue.
> 
> Based on the FSL kernel driver implementation.
> 
> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
> ---
>  arch/arm/include/asm/arch-mx6/iomux.h |  2 ++
>  drivers/pci/pcie_imx.c                | 14 ++++++++++++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/arch/arm/include/asm/arch-mx6/iomux.h
> b/arch/arm/include/asm/arch-mx6/iomux.h index 9b3a91f..e3ef59f 100644
> --- a/arch/arm/include/asm/arch-mx6/iomux.h
> +++ b/arch/arm/include/asm/arch-mx6/iomux.h
> @@ -18,6 +18,8 @@
>  #define IOMUXC_GPR1_REF_SSP_EN			(1 << 16)
>  #define IOMUXC_GPR1_TEST_POWERDOWN		(1 << 18)
> 
> +#define IOMUXC_GPR1_PCIE_SW_RST 		(1 << 29)
> +
>  /*
>   * IOMUXC_GPR5 bit fields
>   */
> diff --git a/drivers/pci/pcie_imx.c b/drivers/pci/pcie_imx.c
> index 1568f20..ddfe389 100644
> --- a/drivers/pci/pcie_imx.c
> +++ b/drivers/pci/pcie_imx.c
> @@ -19,6 +19,7 @@
>  #include <asm/io.h>
>  #include <linux/sizes.h>
>  #include <errno.h>
> +#include <asm/arch/sys_proto.h>
> 
>  #define PCI_ACCESS_READ  0
>  #define PCI_ACCESS_WRITE 1
> @@ -430,6 +431,10 @@ static int imx_pcie_write_config(struct pci_controller
> *hose, pci_dev_t d, static int imx6_pcie_assert_core_reset(void)
>  {
>  	struct iomuxc *iomuxc_regs = (struct iomuxc *)IOMUXC_BASE_ADDR;
> +
> +	if (is_mx6dqp())
> +		setbits_le32(&iomuxc_regs->gpr[1], IOMUXC_GPR1_PCIE_SW_RST);
> +
>  #if defined(CONFIG_MX6SX)
>  	struct gpc *gpc_regs = (struct gpc *)GPC_BASE_ADDR;
> 
> @@ -542,6 +547,15 @@ static int imx6_pcie_deassert_core_reset(void)
>  	 */
>  	mdelay(50);
> 
> +	if (is_mx6dqp()) {
> +		clrbits_le32(&iomuxc_regs->gpr[1], IOMUXC_GPR1_PCIE_SW_RST);

Why don't you put this section before the mdelay(50) above ? This should
produce the same effect as adding additional delay, as you do below, no?

> +		/*
> +		 * some delay is required by 6qp, after the SW_RST is

The sentence should start with capital letter.

> +		 * cleared and before accessing the cfg register.
> +		 */
> +		udelay(200);
> +	}
> +
>  #if defined(CONFIG_MX6SX)
>  	/* SSP_EN is not used on MX6SX anymore */
>  	clrbits_le32(&iomuxc_regs->gpr[12], IOMUXC_GPR12_TEST_POWERDOWN);

Best regards,
Marek Vasut