On Thu, Jan 09, 2020 at 11:28:51AM +0800, Shawn Guo wrote:
> The PCIe reset via GPIO in the driver never worked as expected. Per
> "Power Sequencing and Reset Signal Timings" table in
> PCI EXPRESS CARD ELECTROMECHANICAL SPECIFICATION, the PERST# should be
> deasserted after minimum of 100us once REFCLK is stable.
>
> The assertion has been done when the GPIO is being requested, and
> deassertion should be done in host enabling rather than disabling. Also
> a bit wait is added to ensure device get ready after reset.
>
> Signed-off-by: Shawn Guo <shawn.guo@xxxxxxxxxx>
> ---
> drivers/pci/controller/dwc/pcie-histb.c | 20 ++++++++++++++------
> 1 file changed, 14 insertions(+), 6 deletions(-)
Shawn,
this looks like a fix, please tag it as such and let me know if
it has to be backported, in which case also the previous patch
should I assume.
Thanks,
Lorenzo
> diff --git a/drivers/pci/controller/dwc/pcie-histb.c b/drivers/pci/controller/dwc/pcie-histb.c
> index 112254619ed0..67c27a8036c7 100644
> --- a/drivers/pci/controller/dwc/pcie-histb.c
> +++ b/drivers/pci/controller/dwc/pcie-histb.c
> @@ -219,9 +219,6 @@ static void histb_pcie_host_disable(struct histb_pcie *hipcie)
> clk_disable_unprepare(hipcie->sys_clk);
> clk_disable_unprepare(hipcie->bus_clk);
>
> - if (hipcie->reset_gpio)
> - gpiod_set_value_cansleep(hipcie->reset_gpio, 0);
> -
> if (hipcie->vpcie)
> regulator_disable(hipcie->vpcie);
> }
> @@ -242,9 +239,6 @@ static int histb_pcie_host_enable(struct pcie_port *pp)
> }
> }
>
> - if (hipcie->reset_gpio)
> - gpiod_set_value_cansleep(hipcie->reset_gpio, 1);
> -
> ret = clk_prepare_enable(hipcie->bus_clk);
> if (ret) {
> dev_err(dev, "cannot prepare/enable bus clk\n");
> @@ -278,6 +272,20 @@ static int histb_pcie_host_enable(struct pcie_port *pp)
> reset_control_assert(hipcie->bus_reset);
> reset_control_deassert(hipcie->bus_reset);
>
> + if (hipcie->reset_gpio) {
> + /*
> + * "Power Sequencing and Reset Signal Timings" table in
> + * PCI EXPRESS CARD ELECTROMECHANICAL SPECIFICATION, indicates
> + * PERST# should be deasserted after minimum of 100us
> + * once REFCLK is stable.
> + */
> + usleep_range(100, 200);
> + gpiod_set_value_cansleep(hipcie->reset_gpio, 0);
> +
> + /* wait 1ms for device to be ready */
> + usleep_range(1000, 2000);
> + }
> +
> return 0;
>
> err_aux_clk:
> --
> 2.17.1
>
