From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiko Stuebner Subject: Re: [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS. Date: Fri, 01 Mar 2019 16:59:25 +0100 Message-ID: <2706069.0FZLJLT2V8@phil> References: <20190301153348.29870-1-christoph.muellner@theobroma-systems.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <20190301153348.29870-1-christoph.muellner@theobroma-systems.com> Sender: linux-kernel-owner@vger.kernel.org To: Christoph Muellner Cc: robh+dt@kernel.org, mark.rutland@arm.com, shawn.lin@rock-chips.com, Philipp Tomsich , Kishon Vijay Abraham I , Enric Balletbo i Serra , Klaus Goger , Douglas Anderson , Viresh Kumar , Matthias Brugger , Emil Renner Berthing , Tony Xie , Randy Li , Vicente Bergas , Ezequiel Garcia , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org List-Id: devicetree@vger.kernel.org Hi Christoph, Am Freitag, 1. März 2019, 16:33:43 CET schrieb Christoph Muellner: > The rockchip-emmc PHY can be configured with different > drive impedance values. Currenlty a value of 50 Ohm is > hard coded into the driver. > > This patch introduces the DTS property 'drive-impedance-ohm' > for the rockchip-emmc phy node, which uses the value from the DTS > to setup the drive impedance accordingly. > > Signed-off-by: Christoph Muellner > Signed-off-by: Philipp Tomsich > --- > drivers/phy/rockchip/phy-rockchip-emmc.c | 38 ++++++++++++++++++++++++++++++-- looks good on first glance, but is missing an addition to the emmc-phy devicetree binding in Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt Heiko > 1 file changed, 36 insertions(+), 2 deletions(-) > > diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c > index 19bf84f0bc67..5413fa73dd45 100644 > --- a/drivers/phy/rockchip/phy-rockchip-emmc.c > +++ b/drivers/phy/rockchip/phy-rockchip-emmc.c > @@ -87,6 +87,7 @@ struct rockchip_emmc_phy { > unsigned int reg_offset; > struct regmap *reg_base; > struct clk *emmcclk; > + unsigned int drive_impedance; > }; > > static int rockchip_emmc_phy_power(struct phy *phy, bool on_off) > @@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy) > { > struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy); > > - /* Drive impedance: 50 Ohm */ > + /* Drive impedance: from DTS */ > regmap_write(rk_phy->reg_base, > rk_phy->reg_offset + GRF_EMMCPHY_CON6, > - HIWORD_UPDATE(PHYCTRL_DR_50OHM, > + HIWORD_UPDATE(rk_phy->drive_impedance, > PHYCTRL_DR_MASK, > PHYCTRL_DR_SHIFT)); > > @@ -314,6 +315,28 @@ static const struct phy_ops ops = { > .owner = THIS_MODULE, > }; > > +static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm) > +{ > + switch (dr_ohm) { > + case 100: > + return PHYCTRL_DR_100OHM; > + case 66: > + return PHYCTRL_DR_66OHM; > + case 50: > + return PHYCTRL_DR_50OHM; > + case 40: > + return PHYCTRL_DR_40OHM; > + case 33: > + return PHYCTRL_DR_33OHM; > + } > + > + dev_warn(&pdev->dev, > + "Invalid value %u for drive-impedance-ohm. " > + "Falling back to 50 Ohm.\n", > + dr_ohm); > + return PHYCTRL_DR_50OHM; > +} > + > static int rockchip_emmc_phy_probe(struct platform_device *pdev) > { > struct device *dev = &pdev->dev; > @@ -322,6 +345,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev) > struct phy_provider *phy_provider; > struct regmap *grf; > unsigned int reg_offset; > + u32 val; > > if (!dev->parent || !dev->parent->of_node) > return -ENODEV; > @@ -345,6 +369,16 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev) > rk_phy->reg_offset = reg_offset; > rk_phy->reg_base = grf; > > + if (of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val)) { > + dev_info(dev, > + "Missing drive-impedance-ohm property in node %s " > + "Falling back to 50 Ohm.\n", > + dev->of_node->name); > + rk_phy->drive_impedance = PHYCTRL_DR_50OHM; > + } else { > + rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val); > + } > + > generic_phy = devm_phy_create(dev, dev->of_node, &ops); > if (IS_ERR(generic_phy)) { > dev_err(dev, "failed to create PHY\n"); >