> -----Original Message----- > From: Linus Walleij <linus.walleij@xxxxxxxxxx> > Sent: 2024年5月6日 20:10 > To: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > Cc: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>; Frank Li > <frank.li@xxxxxxx>; Krzysztof Wilczyński <kwilczynski@xxxxxxxxxx>; Uwe > Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>; linux-omap@xxxxxxxxxxxxxxx; > linux-pci@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx; > linux-amlogic@xxxxxxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx; > linux-tegra@xxxxxxxxxxxxxxx; Vignesh Raghavendra <vigneshr@xxxxxx>; > Siddharth Vadapalli <s-vadapalli@xxxxxx>; Lorenzo Pieralisi > <lpieralisi@xxxxxxxxxx>; Krzysztof Wilczyński <kw@xxxxxxxxx>; Rob Herring > <robh@xxxxxxxxxx>; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; Hongxing Zhu > <hongxing.zhu@xxxxxxx>; Lucas Stach <l.stach@xxxxxxxxxxxxxx>; Shawn Guo > <shawnguo@xxxxxxxxxx>; Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>; Pengutronix > Kernel Team <kernel@xxxxxxxxxxxxxx>; Fabio Estevam <festevam@xxxxxxxxx>; > Yue Wang <yue.wang@xxxxxxxxxxx>; Neil Armstrong > <neil.armstrong@xxxxxxxxxx>; Kevin Hilman <khilman@xxxxxxxxxxxx>; Jerome > Brunet <jbrunet@xxxxxxxxxxxx>; Martin Blumenstingl > <martin.blumenstingl@xxxxxxxxxxxxxx>; Xiaowei Song > <songxiaowei@xxxxxxxxxxxxx>; Binghui Wang <wangbinghui@xxxxxxxxxxxxx>; > Thierry Reding <thierry.reding@xxxxxxxxx>; Jonathan Hunter > <jonathanh@xxxxxxxxxx>; Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxx>; > Pali Rohár <pali@xxxxxxxxxx> > Subject: Re: [PATCH v3 4/5] PCI: imx6: Convert to agnostic GPIO API > > On Mon, Apr 29, 2024 at 12:25 PM Andy Shevchenko > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote: > > > The of_gpio.h is going to be removed. In preparation of that convert > > the driver to the agnostic API. > > > > Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> > > Reviewed-by: Frank Li <Frank.Li@xxxxxxx> > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > > I think there is a bug here, the code is respecting the OF property > "reset-gpio-active-high" Yes, you're right. As I remember that this property is used for the buggy hardware design. In general implementation, the PERST# is active low. In pci_imx6 driver, it used to call the following callbacks to toggle perst# gpio_set_value_cansleep(imx6_pcie->reset_gpio, 0); msleep(100); gpio_set_value_cansleep(imx6_pcie->reset_gpio, 1); But, some buggy hardware designs use this GPIO signal active high. And the correct toggle sequence for thos board is reversed. gpio_set_value_cansleep(imx6_pcie->reset_gpio, 1); msleep(100); gpio_set_value_cansleep(imx6_pcie->reset_gpio, 0); So, this property is added for those buggy hardware designs. Best Regards Richard Zhu > but the code in drivers/gpio/gpiolib-of.h actually has a quirk for this so you can > just delete all the active high handling and rely on 1 = asserted and 0 = deasserted > when using GPIO descriptors. > > Just delete this thing: > imx6_pcie->gpio_active_high = of_property_read_bool(node, > "reset-gpio-active-high"); > > Yours, > Linus Walleij
