From 940f83cc8d899551dec22e3d9142e9e7022c29ac Mon Sep 17 00:00:00 2001 From: Daniel Golle Date: Tue, 30 Jul 2024 00:37:21 +0100 Subject: [PATCH] rockchip: dw-rockchip: Fix initial PERST# GPIO value Import patch from mainline Linux to fix issue with PERST# signal polarity. Quote from commit message: "This extra, very short, PERST# assertion + deassertion has been reported to cause issues with certain WLAN controllers, e.g. RTL8822CE." Signed-off-by: Daniel Golle --- ...ockchip-Fix-initial-PERST-GPIO-value.patch | 76 +++++++++++++++++++ 1 file changed, 76 insertions(+) create mode 100644 target/linux/rockchip/patches-6.6/310-PCI-dw-rockchip-Fix-initial-PERST-GPIO-value.patch diff --git a/target/linux/rockchip/patches-6.6/310-PCI-dw-rockchip-Fix-initial-PERST-GPIO-value.patch b/target/linux/rockchip/patches-6.6/310-PCI-dw-rockchip-Fix-initial-PERST-GPIO-value.patch new file mode 100644 index 0000000000..5ebf04bb33 --- /dev/null +++ b/target/linux/rockchip/patches-6.6/310-PCI-dw-rockchip-Fix-initial-PERST-GPIO-value.patch @@ -0,0 +1,76 @@ +From 28b8d7793b8573563b3d45321376f36168d77b1e Mon Sep 17 00:00:00 2001 +From: Niklas Cassel +Date: Wed, 17 Apr 2024 18:42:26 +0200 +Subject: [PATCH] PCI: dw-rockchip: Fix initial PERST# GPIO value +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +PERST# is active low according to the PCIe specification. + +However, the existing pcie-dw-rockchip.c driver does: + + gpiod_set_value(..., 0); msleep(100); gpiod_set_value(..., 1); + +when asserting + deasserting PERST#. + +This is of course wrong, but because all the device trees for this +compatible string have also incorrectly marked this GPIO as ACTIVE_HIGH: + + $ git grep -B 10 reset-gpios arch/arm64/boot/dts/rockchip/rk3568* + $ git grep -B 10 reset-gpios arch/arm64/boot/dts/rockchip/rk3588* + +The actual toggling of PERST# is correct, and we cannot change it anyway, +since that would break device tree compatibility. + +However, this driver does request the GPIO to be initialized as +GPIOD_OUT_HIGH, which does cause a silly sequence where PERST# gets +toggled back and forth for no good reason. + +Fix this by requesting the GPIO to be initialized as GPIOD_OUT_LOW (which +for this driver means PERST# asserted). + +This will avoid an unnecessary signal change where PERST# gets deasserted +(by devm_gpiod_get_optional()) and then gets asserted (by +rockchip_pcie_start_link()) just a few instructions later. + +Before patch, debug prints on EP side, when booting RC: + + [ 845.606810] pci: PERST# asserted by host! + [ 852.483985] pci: PERST# de-asserted by host! + [ 852.503041] pci: PERST# asserted by host! + [ 852.610318] pci: PERST# de-asserted by host! + +After patch, debug prints on EP side, when booting RC: + + [ 125.107921] pci: PERST# asserted by host! + [ 132.111429] pci: PERST# de-asserted by host! + +This extra, very short, PERST# assertion + deassertion has been reported to +cause issues with certain WLAN controllers, e.g. RTL8822CE. + +Fixes: 0e898eb8df4e ("PCI: rockchip-dwc: Add Rockchip RK356X host controller driver") +Link: https://lore.kernel.org/linux-pci/20240417164227.398901-1-cassel@kernel.org +Tested-by: Heiko Stuebner +Tested-by: Jianfeng Liu +Signed-off-by: Niklas Cassel +Signed-off-by: Krzysztof Wilczyński +Signed-off-by: Bjorn Helgaas +Reviewed-by: Heiko Stuebner +Reviewed-by: Manivannan Sadhasivam +Cc: stable@vger.kernel.org # v5.15+ +--- + drivers/pci/controller/dwc/pcie-dw-rockchip.c | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +--- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c ++++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c +@@ -240,7 +240,7 @@ static int rockchip_pcie_resource_get(st + return PTR_ERR(rockchip->apb_base); + + rockchip->rst_gpio = devm_gpiod_get_optional(&pdev->dev, "reset", +- GPIOD_OUT_HIGH); ++ GPIOD_OUT_LOW); + if (IS_ERR(rockchip->rst_gpio)) + return PTR_ERR(rockchip->rst_gpio); + -- 2.30.2