From cffd3ad8d7cad2214d44695ad4f2405ea53a26c7 Mon Sep 17 00:00:00 2001 From: Martin Schiller Date: Mon, 6 May 2024 11:01:15 +0200 Subject: [PATCH] lantiq: add patch to fix the reset gpio handling in the pci driver Linux kernel commit 90c2d2eb7ab5 ("MIPS: pci: lantiq: switch to using gpiod API") not only switched to the gpiod API, but also inverted / changed the polarity of the GPIO. According to the PCI specification, the RST# pin is an active-low signal. However, most of the device trees that have been widely used for a long time (mainly in the openWrt project) define this GPIO as active-high and the old driver code inverted the signal internally. Apparently there are actually boards where the reset gpio must be operated inverted. For this reason, we cannot use the GPIOD_OUT_LOW/HIGH flag for initialization. Instead, we must explicitly set the gpio to value 1 in order to take into account any "GPIO_ACTIVE_LOW" flag that may have been set. In order to remain compatible with all these existing device trees, we should therefore keep the logic as it was before the commit. Signed-off-by: Martin Schiller --- ...i-lantiq-restore-reset-gpio-polarity.patch | 62 +++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 target/linux/lantiq/patches-6.1/0002-MIPS-pci-lantiq-restore-reset-gpio-polarity.patch diff --git a/target/linux/lantiq/patches-6.1/0002-MIPS-pci-lantiq-restore-reset-gpio-polarity.patch b/target/linux/lantiq/patches-6.1/0002-MIPS-pci-lantiq-restore-reset-gpio-polarity.patch new file mode 100644 index 000000000000..6b70f8b9a7b7 --- /dev/null +++ b/target/linux/lantiq/patches-6.1/0002-MIPS-pci-lantiq-restore-reset-gpio-polarity.patch @@ -0,0 +1,62 @@ +From f038380835033e376d89c72516f087254792bbad Mon Sep 17 00:00:00 2001 +From: Martin Schiller +Date: Mon, 6 May 2024 09:41:42 +0200 +Subject: [PATCH] MIPS: pci: lantiq: restore reset gpio polarity + +Commit 90c2d2eb7ab5 ("MIPS: pci: lantiq: switch to using gpiod API") not +only switched to the gpiod API, but also inverted / changed the polarity +of the GPIO. + +According to the PCI specification, the RST# pin is an active-low +signal. However, most of the device trees that have been widely used for +a long time (mainly in the openWrt project) define this GPIO as +active-high and the old driver code inverted the signal internally. + +Apparently there are actually boards where the reset gpio must be +operated inverted. For this reason, we cannot use the GPIOD_OUT_LOW/HIGH +flag for initialization. Instead, we must explicitly set the gpio to +value 1 in order to take into account any "GPIO_ACTIVE_LOW" flag that +may have been set. + +In order to remain compatible with all these existing device trees, we +should therefore keep the logic as it was before the commit. + +Fixes: 90c2d2eb7ab5 ("MIPS: pci: lantiq: switch to using gpiod API") +Cc: stable@vger.kernel.org +Signed-off-by: Martin Schiller +--- + arch/mips/pci/pci-lantiq.c | 8 ++++---- + 1 file changed, 4 insertions(+), 4 deletions(-) + +--- a/arch/mips/pci/pci-lantiq.c ++++ b/arch/mips/pci/pci-lantiq.c +@@ -124,14 +124,14 @@ static int ltq_pci_startup(struct platfo + clk_disable(clk_external); + + /* setup reset gpio used by pci */ +- reset_gpio = devm_gpiod_get_optional(&pdev->dev, "reset", +- GPIOD_OUT_LOW); ++ reset_gpio = devm_gpiod_get_optional(&pdev->dev, "reset", GPIOD_ASIS); + error = PTR_ERR_OR_ZERO(reset_gpio); + if (error) { + dev_err(&pdev->dev, "failed to request gpio: %d\n", error); + return error; + } + gpiod_set_consumer_name(reset_gpio, "pci_reset"); ++ gpiod_direction_output(reset_gpio, 1); + + /* enable auto-switching between PCI and EBU */ + ltq_pci_w32(0xa, PCI_CR_CLK_CTRL); +@@ -194,10 +194,10 @@ static int ltq_pci_startup(struct platfo + + /* toggle reset pin */ + if (reset_gpio) { +- gpiod_set_value_cansleep(reset_gpio, 1); ++ gpiod_set_value_cansleep(reset_gpio, 0); + wmb(); + mdelay(1); +- gpiod_set_value_cansleep(reset_gpio, 0); ++ gpiod_set_value_cansleep(reset_gpio, 1); + } + return 0; + } -- 2.30.2