From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 4 Jun 2019 15:22:33 +0200 From: Thierry Reding Subject: Re: [PATCH V4 27/28] PCI: tegra: Add support for GPIO based PERST# Message-ID: <20190604132233.GT16519@ulmo> References: <20190516055307.25737-1-mmaddireddy@nvidia.com> <20190516055307.25737-28-mmaddireddy@nvidia.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="VjP/dwTbBl6I9PQk" Content-Disposition: inline In-Reply-To: <20190516055307.25737-28-mmaddireddy@nvidia.com> To: Manikanta Maddireddy Cc: bhelgaas@google.com, robh+dt@kernel.org, mark.rutland@arm.com, jonathanh@nvidia.com, lorenzo.pieralisi@arm.com, vidyas@nvidia.com, linux-tegra@vger.kernel.org, linux-pci@vger.kernel.org, devicetree@vger.kernel.org List-ID: --VjP/dwTbBl6I9PQk Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 16, 2019 at 11:23:06AM +0530, Manikanta Maddireddy wrote: > Add support for GPIO based PERST# signal. GPIO number comes from per port > PCIe device tree node. >=20 > Signed-off-by: Manikanta Maddireddy > --- > V4: Using devm_gpiod_get_from_of_node() to get reset-gpios >=20 > V3: Using helper function to get reset-gpios >=20 > V2: Using standard "reset-gpio" property >=20 > drivers/pci/controller/pci-tegra.c | 41 +++++++++++++++++++++++++----- > 1 file changed, 35 insertions(+), 6 deletions(-) >=20 > diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/= pci-tegra.c > index 06b99fcbf382..09b4d384ba38 100644 > --- a/drivers/pci/controller/pci-tegra.c > +++ b/drivers/pci/controller/pci-tegra.c > @@ -17,6 +17,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -400,6 +401,8 @@ struct tegra_pcie_port { > unsigned int lanes; > =20 > struct phy **phys; > + > + struct gpio_desc *reset_gpiod; Nit: I'd leave away the "d" at the end there. Or perhaps even the _gpio suffix entirely. But it's fine either way. > }; > =20 > struct tegra_pcie_bus { > @@ -583,15 +586,23 @@ static void tegra_pcie_port_reset(struct tegra_pcie= _port *port) > unsigned long value; > =20 > /* pulse reset signal */ > - value =3D afi_readl(port->pcie, ctrl); > - value &=3D ~AFI_PEX_CTRL_RST; > - afi_writel(port->pcie, value, ctrl); > + if (port->reset_gpiod) { > + gpiod_set_value(port->reset_gpiod, 0); So is this actually deasserting the reset pin, or is it asserting a low-active reset? I think it's the latter, because ... > + } else { > + value =3D afi_readl(port->pcie, ctrl); > + value &=3D ~AFI_PEX_CTRL_RST; > + afi_writel(port->pcie, value, ctrl); > + } > =20 > usleep_range(1000, 2000); > =20 > - value =3D afi_readl(port->pcie, ctrl); > - value |=3D AFI_PEX_CTRL_RST; > - afi_writel(port->pcie, value, ctrl); > + if (port->reset_gpiod) { > + gpiod_set_value(port->reset_gpiod, 1); After this the port should be functional, right? I think it'd be better to reverse the logic here and move the polarity of the GPIO into device tree. gpiod_set_value() takes care of inverting the level internally if the GPIO is marked as low-active in DT. The end result is obviously the same, but it makes the usage much clearer. If somebody want to write a DT for their board, they will look at the schematics and see a low-active reset line and may be tempted to describe it as such in DT, but with your current code that would be exactly the wrong way around. > + } else { > + value =3D afi_readl(port->pcie, ctrl); > + value |=3D AFI_PEX_CTRL_RST; > + afi_writel(port->pcie, value, ctrl); > + } > } > =20 > static void tegra_pcie_enable_rp_features(struct tegra_pcie_port *port) > @@ -2238,6 +2249,7 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *p= cie) > struct tegra_pcie_port *rp; > unsigned int index; > u32 value; > + char *label; > =20 > err =3D of_pci_get_devfn(port); > if (err < 0) { > @@ -2296,6 +2308,23 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *= pcie) > if (IS_ERR(rp->base)) > return PTR_ERR(rp->base); > =20 > + label =3D kasprintf(GFP_KERNEL, "pex-reset-%u", index); devm_kasprintf()? Thierry > + if (!label) { > + dev_err(dev, "failed to create reset GPIO label\n"); > + return -ENOMEM; > + } > + > + rp->reset_gpiod =3D devm_gpiod_get_from_of_node(dev, port, > + "reset-gpios", 0, > + GPIOD_OUT_LOW, > + label); > + kfree(label); > + if (IS_ERR(rp->reset_gpiod)) { > + err =3D PTR_ERR(rp->reset_gpiod); > + dev_err(dev, "failed to get reset GPIO: %d\n", err); > + return err; > + } > + > list_add_tail(&rp->list, &pcie->ports); > } > =20 > --=20 > 2.17.1 >=20 --VjP/dwTbBl6I9PQk Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAlz2cJkACgkQ3SOs138+ s6HSFw//eP/VCDXncQLm+r5DEpanlW+Sq3fRXMjdM9VBwcndbfAme7NHXjnOzXiv 6wCwXa9PD/DVqV9hAt7Vp4rmaBqrIGZGv8RL+74qpawXfCfUBmmDsIkRsWkCGa5c GtSnisdLeYkjmk0cL4djm78yRQOiFcKe1xQIfJ4iK4NJHO92KhUbi4TDUx1d2fHM Q33r7jd8U536pLi0GMmENddS6Zy6tzp7j9rGbRHpkAdNQkv9dKUAVEONT5CpWhjM KCmFNFOb7uo68sIBXUSQUuhKEt1+j779vlKkTQovih4LjyDmt4bDrnmGrwpu6H2U 8xik/vrigI6vrda5y8aeSCHPMMez/rybl9t2av8gEX4auOus7Q19IKQmDeCaM2/w ecobgKwHb6teyJhYVW99igSKZps6bLNiM9SMmQ2bQ5nrA2G0mJNB52/Vywn2CR4k GKtnNSIh9QA5pR3Ib6VhWRlYQ6J+tBB6iW0nqoWvyZVXd0t3mUerin8whik9xS/w PKKSzuUtztt0Bv0qGcGnlI9kr7h6NU20rilC8WC3ZsSDEA18N9okKFlU2o4IsMWd 2GIPJjqTuWewusxLv19Xj6zknZXNoU+acWFBCwq9WuqZccTZlEl0cYffdyoBuTB/ 4IGYVsrmA51fq+hIPM9yQgyjm/+REYfGAhVYyUj1wXM0NnwWdEM= =fEUv -----END PGP SIGNATURE----- --VjP/dwTbBl6I9PQk--