Re: [PATCH v4 2/2] PCI: rockchip-host: Wait 100ms after reset before starting configuration

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Sat, Apr 13, 2024 at 09:41:20AM +0900, Damien Le Moal wrote:
> The PCI Express Base Specification r6.0, section 6.6.1, states that the
> host should wait for at least 100 msec from the end of a conventional
> reset (PERST# is de-asserted) before sending a configuration request to
> ensure that the device is able to respond with a "Request Retry Status"
> completion.
> 
> Add the PCIE_T_RRS_READY_MS macro to define this wait time and modify
> rockchip_pcie_host_init_port() to add this 100ms sleep after deasserting
> PERST# using the ep_gpio GPIO.
> 
> Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
>  drivers/pci/controller/pcie-rockchip-host.c | 2 ++
>  drivers/pci/pci.h                           | 7 +++++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c
> index fc868251e570..cbec71114825 100644
> --- a/drivers/pci/controller/pcie-rockchip-host.c
> +++ b/drivers/pci/controller/pcie-rockchip-host.c
> @@ -325,6 +325,8 @@ static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip)
>  	msleep(PCIE_T_PVPERL_MS);
>  	gpiod_set_value_cansleep(rockchip->ep_gpio, 1);
>  
> +	msleep(PCIE_T_RRS_READY_MS);
> +
>  	/* 500ms timeout value should be enough for Gen1/2 training */
>  	err = readl_poll_timeout(rockchip->apb_base + PCIE_CLIENT_BASIC_STATUS1,
>  				 status, PCIE_LINK_UP(status), 20,
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 17fed1846847..c93ffc5e6e1f 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -16,6 +16,13 @@
>  /* Power stable to PERST# inactive from PCIe card Electromechanical Spec */
>  #define PCIE_T_PVPERL_MS		100
>  
> +/*
> + * End of conventional reset (PERST# de-asserted) to first configuration
> + * request (device able to respond with a "Request Retry Status" completion),
> + * from PCI Express Base Specification r6.0, section 6.6.1.
> + */
> +#define PCIE_T_RRS_READY_MS	100
> +
>  /*
>   * PCIe r6.0, sec 5.3.3.2.1 <PME Synchronization>
>   * Recommends 1ms to 10ms timeout to check L2 ready.
> -- 
> 2.44.0
> 
> 

-- 
மணிவண்ணன் சதாசிவம்

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel