| Message ID | 20210517153557.429623-1-luca@lucaceresoli.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | PCI: dwc: pci-dra7xx: fix reset behaviour | expand |
diff --git a/drivers/pci/controller/dwc/pci-dra7xx.c b/drivers/pci/controller/dwc/pci-dra7xx.c index dacd6da70c35..8dd20b394d0c 100644 --- a/drivers/pci/controller/dwc/pci-dra7xx.c +++ b/drivers/pci/controller/dwc/pci-dra7xx.c @@ -800,6 +800,8 @@ static int dra7xx_pcie_probe(struct platform_device *pdev) dev_err(&pdev->dev, "gpio request failed, ret %d\n", ret); goto err_gpio; } + usleep_range(1000, 2000); + gpiod_set_value(reset, 0); reg = dra7xx_pcie_readl(dra7xx, PCIECTRL_DRA7XX_CONF_DEVICE_CMD); reg &= ~LTSSM_EN;
The PCIe PERSTn reset pin is active low and should be asserted, then deasserted. The current implementation only drives the pin once in "HIGH" position, thus presumably it was intended to deassert the pin. This has two problems: 1) it assumes the pin was asserted by other means before loading the driver 2) it has the wrong polarity, since "HIGH" means "active", and the pin is presumably configured as active low coherently with the PCIe convention, thus it is driven physically to 0, keeping the device under reset unless the pin is configured as active high. Fix both problems by: 1) keeping devm_gpiod_get_optional(dev, NULL, GPIOD_OUT_HIGH) as is, but assuming the pin is correctly configured as "active low" this now becomes a reset assertion 2) adding gpiod_set_value(reset, 0) after a delay to deassert reset Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net> --- drivers/pci/controller/dwc/pci-dra7xx.c | 2 ++ 1 file changed, 2 insertions(+)