diff options
Diffstat (limited to 'target/linux/mvebu/patches-5.4/402-PCI-aardvark-Wait-for-endpoint-to-be-ready-before-tr.patch')
| -rw-r--r-- | target/linux/mvebu/patches-5.4/402-PCI-aardvark-Wait-for-endpoint-to-be-ready-before-tr.patch | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/target/linux/mvebu/patches-5.4/402-PCI-aardvark-Wait-for-endpoint-to-be-ready-before-tr.patch b/target/linux/mvebu/patches-5.4/402-PCI-aardvark-Wait-for-endpoint-to-be-ready-before-tr.patch new file mode 100644 index 0000000000..95abbce002 --- /dev/null +++ b/target/linux/mvebu/patches-5.4/402-PCI-aardvark-Wait-for-endpoint-to-be-ready-before-tr.patch @@ -0,0 +1,50 @@ +From f4c7d053d7f77cd5c1a1ba7c7ce085ddba13d1d7 Mon Sep 17 00:00:00 2001 +From: Remi Pommarel <repk@triplefau.lt> +Date: Wed, 22 May 2019 23:33:50 +0200 +Subject: [PATCH] PCI: aardvark: Wait for endpoint to be ready before training + link + +When configuring pcie reset pin from gpio (e.g. initially set by +u-boot) to pcie function this pin goes low for a brief moment +asserting the PERST# signal. Thus connected device enters fundamental +reset process and link configuration can only begin after a minimal +100ms delay (see [1]). + +Because the pin configuration comes from the "default" pinctrl it is +implicitly configured before the probe callback is called: + +driver_probe_device() + really_probe() + ... + pinctrl_bind_pins() /* Here pin goes from gpio to PCIE reset + function and PERST# is asserted */ + ... + drv->probe() + +[1] "PCI Express Base Specification", REV. 4.0 + PCI Express, February 19 2014, 6.6.1 Conventional Reset + +Signed-off-by: Remi Pommarel <repk@triplefau.lt> +Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> +Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com> +--- + drivers/pci/controller/pci-aardvark.c | 8 ++++++++ + 1 file changed, 8 insertions(+) + +--- a/drivers/pci/controller/pci-aardvark.c ++++ b/drivers/pci/controller/pci-aardvark.c +@@ -337,6 +337,14 @@ static void advk_pcie_setup_hw(struct ad + reg |= PIO_CTRL_ADDR_WIN_DISABLE; + advk_writel(pcie, reg, PIO_CTRL); + ++ /* ++ * PERST# signal could have been asserted by pinctrl subsystem before ++ * probe() callback has been called, making the endpoint going into ++ * fundamental reset. As required by PCI Express spec a delay for at ++ * least 100ms after such a reset before link training is needed. ++ */ ++ msleep(PCI_PM_D3COLD_WAIT); ++ + /* Start link training */ + reg = advk_readl(pcie, PCIE_CORE_LINK_CTRL_STAT_REG); + reg |= PCIE_CORE_LINK_TRAINING; |