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Date: Wed, 30 Jan 2019 10:53:32 +0100
From: Jorge Ramirez <jorge.ramirez-ortiz@...aro.org>
To: Bjorn Andersson <bjorn.andersson@...aro.org>
Cc: gregkh@...uxfoundation.org, mark.rutland@....com, kishon@...com,
jackp@...eaurora.org, andy.gross@...aro.org, swboyd@...omium.org,
shawn.guo@...aro.org, vkoul@...nel.org, khasim.mohammed@...aro.org,
devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] phy: qualcomm: usb: Add Super-Speed PHY driver
On 1/29/19 21:27, Bjorn Andersson wrote:
> On Tue 29 Jan 03:35 PST 2019, Jorge Ramirez-Ortiz wrote:
>> diff --git a/drivers/phy/qualcomm/phy-qcom-usb-ss.c b/drivers/phy/qualcomm/phy-qcom-usb-ss.c
>> new file mode 100644
>> index 0000000..e6ae96e
>> --- /dev/null
>> +++ b/drivers/phy/qualcomm/phy-qcom-usb-ss.c
>> @@ -0,0 +1,347 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2012-2014,2017 The Linux Foundation. All rights reserved.
>> + * Copyright (c) 2018, Linaro Limited
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/phy/phy.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <linux/reset.h>
>> +#include <linux/slab.h>
>> +
>> +#define PHY_CTRL0 0x6C
>> +#define PHY_CTRL1 0x70
>> +#define PHY_CTRL2 0x74
>> +#define PHY_CTRL4 0x7C
>> +
>> +/* PHY_CTRL bits */
>> +#define REF_PHY_EN BIT(0)
>> +#define LANE0_PWR_ON BIT(2)
>> +#define SWI_PCS_CLK_SEL BIT(4)
>> +#define TST_PWR_DOWN BIT(4)
>> +#define PHY_RESET BIT(7)
>> +
>> +enum phy_vdd_ctrl { ENABLE, DISABLE, };
>
> Use bool to describe boolean values.
um, ok, but these are not booleans, they are actions (ie ctrl = action
not true or false).
anyway will change it to something else
>
>> +enum phy_regulator { VDD, VDDA1P8, };
>
> It doesn't look like you need either of these if you remove the
> set_voltage calls.
we need to point to the regulator in the array so we need an index to it
somehow.
>
>> +
>> +struct ssphy_priv {
>> + void __iomem *base;
>> + struct device *dev;
>> + struct reset_control *reset_com;
>> + struct reset_control *reset_phy;
>> + struct regulator *vbus;
>> + struct regulator_bulk_data *regs;
>> + int num_regs;
>> + struct clk_bulk_data *clks;
>> + int num_clks;
>> + enum phy_mode mode;
>> +};
>> +
>> +static inline void qcom_ssphy_updatel(void __iomem *addr, u32 mask, u32 val)
>> +{
>> + writel((readl(addr) & ~mask) | val, addr);
>> +}
>> +
>> +static inline int qcom_ssphy_vbus_enable(struct regulator *vbus)
>> +{
>> + return !regulator_is_enabled(vbus) ? regulator_enable(vbus) : 0;
>
> regulator_is_enabled() will check if the actual regulator is on, not if
> you already voted for it.
>
> So if something else is enabling the vbus regulator you will skip your
> enable and be in the mercy of them not releasing it. Presumably there's
> only one consumer of this particular regulator, but it's a bad habit.
yep
>
> Please keep track of this drivers requested state in this driver, if
> qcom_ssphy_vbus_ctrl() is called not only for the state changes.
um, there is not such a function: the ctrl function is not for vbus but
for vdd
>
>> +}
>> +
>> +static inline int qcom_ssphy_vbus_disable(struct regulator *vbus)
>> +{
>> + return regulator_is_enabled(vbus) ? regulator_disable(vbus) : 0;
>> +}
>> +
>> +static int qcom_ssphy_vdd_ctrl(struct ssphy_priv *priv, enum phy_vdd_ctrl ctrl)
>
> As discussed on IRC, I think you should just leave the voltage
> constraints to DeviceTree.
yes
>
>> +{
>> + const int vdd_min = ctrl == ENABLE ? 1050000 : 0;
>> + const int vdd_max = 1050000;
>> + int ret;
>> +
>> + ret = regulator_set_voltage(priv->regs[VDD].consumer, vdd_min, vdd_max);
>> + if (ret)
>> + dev_err(priv->dev, "Failed to set regulator vdd to %d\n",
>> + vdd_min);
>> +
>> + return ret;
>> +}
> [..]
>> +static int qcom_ssphy_power_on(struct phy *phy)
>> +{
>> + struct ssphy_priv *priv = phy_get_drvdata(phy);
>> + int ret;
>> +
>> + ret = qcom_ssphy_vdd_ctrl(priv, ENABLE);
>> + if (ret)
>> + return ret;
>> +
>> + ret = regulator_bulk_enable(priv->num_regs, priv->regs);
>> + if (ret)
>> + goto err1;
>> +
>> + ret = clk_bulk_prepare_enable(priv->num_clks, priv->clks);
>> + if (ret)
>> + goto err2;
>> +
>> + ret = qcom_ssphy_vbus_ctrl(priv->vbus, priv->mode);
>> + if (ret)
>> + goto err3;
>> +
>> + ret = qcom_ssphy_do_reset(priv);
>> + if (ret)
>> + goto err4;
>> +
>> + writeb(SWI_PCS_CLK_SEL, priv->base + PHY_CTRL0);
>> + qcom_ssphy_updatel(priv->base + PHY_CTRL4, LANE0_PWR_ON, LANE0_PWR_ON);
>> + qcom_ssphy_updatel(priv->base + PHY_CTRL2, REF_PHY_EN, REF_PHY_EN);
>> + qcom_ssphy_updatel(priv->base + PHY_CTRL4, TST_PWR_DOWN, 0);
>> +
>> + return 0;
>> +err4:
>
> Name your labels based on what they do, e.g. err_disable_vbus.
ok
>
>> + if (priv->vbus && priv->mode != PHY_MODE_INVALID)
>> + qcom_ssphy_vbus_disable(priv->vbus);
>
> qcom_ssphy_vbus_ctrl() above was either enabling or disabling vbus, but
> here you're directly calling disable to unroll that. It think the result
> is correct (in host this reverts to disabled and in gadget it's a
> no-op), but I'm not sure I like the design of sometimes calling straight
> to the vbus enable/disable and sometimes to the wrapper function.
I think you misread: we have vbus enable/disable and vdd control
(different regulators)
I have to admit that the only reason I had separate functions for vbus
enable/disable was cosmetic (and "if" on the control variable + another
"if" to check that the regulator was already voted was taking me beyond
the 80 lines character and I hate when that happens on simple
operations). anyway will redo
>
>> +err3:
>
> err_clk_disable
>
>> + clk_bulk_disable_unprepare(priv->num_clks, priv->clks);
>> +err2:
>> + regulator_bulk_disable(priv->num_regs, priv->regs);
>> +err1:
>> + qcom_ssphy_vdd_ctrl(priv, DISABLE);
>> +
>> + return ret;
>> +}
>> +
>> +static int qcom_ssphy_power_off(struct phy *phy)
>> +{
>> + struct ssphy_priv *priv = phy_get_drvdata(phy);
>> +
>> + qcom_ssphy_updatel(priv->base + PHY_CTRL4, LANE0_PWR_ON, 0);
>> + qcom_ssphy_updatel(priv->base + PHY_CTRL2, REF_PHY_EN, 0);
>> + qcom_ssphy_updatel(priv->base + PHY_CTRL4, TST_PWR_DOWN, TST_PWR_DOWN);
>> +
>> + clk_bulk_disable_unprepare(priv->num_clks, priv->clks);
>> + regulator_bulk_disable(priv->num_regs, priv->regs);
>> +
>> + if (priv->vbus && priv->mode != PHY_MODE_INVALID)
>> + qcom_ssphy_vbus_disable(priv->vbus);
>> +
>> + qcom_ssphy_vdd_ctrl(priv, DISABLE);
>> +
>> + return 0;
>> +}
>> +
>> +static int qcom_ssphy_init_clock(struct ssphy_priv *priv)
>> +{
>> + const char * const clk_id[] = { "ref", "phy", "pipe", };
>> + int i;
>> +
>> + priv->num_clks = ARRAY_SIZE(clk_id);
>> + priv->clks = devm_kcalloc(priv->dev, priv->num_clks,
>> + sizeof(*priv->clks), GFP_KERNEL);
>
> You know num_clks is 3, so I would suggest that you just change the
> sshphy_priv to clks[3] and skip the dynamic allocation.
ok
>
>
> Also, as num_clks always is ARRAY_SIZE(priv->clks) I would suggest using
> the latter, to make that clear throughout the driver.
maybe then just define NBR_CLKS (I find long lines a pain to read)
>
>> + if (!priv->clks)
>> + return -ENOMEM;
>> +
>> + for (i = 0; i < priv->num_clks; i++)
>> + priv->clks[i].id = clk_id[i];
>
> There's no harm in just writing this on three lines:
>
> priv->clks[0].id = "ref";
> priv->clks[1].id = "phy";
> priv->clks[2].id = "pipe";
>
>> +
>> + return devm_clk_bulk_get(priv->dev, priv->num_clks, priv->clks);
>> +}
>> +
>> +static int qcom_ssphy_init_regulator(struct ssphy_priv *priv)
>> +{
>> + const char * const reg_supplies[] = {
>> + [VDD] = "vdd",
>> + [VDDA1P8] = "vdda1p8",
>> + };
>> + int ret, i;
>> +
>> + priv->num_regs = ARRAY_SIZE(reg_supplies);
>> + priv->regs = devm_kcalloc(priv->dev, priv->num_regs,
>> + sizeof(*priv->regs), GFP_KERNEL);
>
> As with clocks, you know there will only be 2 of these, make it fixed
> size in ssphy_priv.
well ok
>
> And as with clocks, I would suggest using ARRAY_SIZE(priv->regs)
> throughout the driver to make it obvious that's it's a static number.
>
>> + if (!priv->regs)
>> + return -ENOMEM;
>> +
>> + for (i = 0; i < priv->num_regs; i++)
>> + priv->regs[i].supply = reg_supplies[i];
>
> As with clocks, just unroll this and fill in the 2 supplies directly.
um, ok, I find the above more readable but I see where you are going
with these sort of recomendations...will just follow them
>
>> +
>> + ret = devm_regulator_bulk_get(priv->dev, priv->num_regs, priv->regs);
>> + if (ret)
>> + return ret;
>> +
>> + priv->vbus = devm_regulator_get_optional(priv->dev, "vbus");
>
> get_optional means that if vbus-supply is not found, rather than
> returning a dummy regulator object this will fail with -ENODEV.
yes I messed this up.
>
> Given the rest of the logic related to vbus you should set vbus to NULL
> if the returned PTR_ERR(value) is -ENODEV, and fail for other errors.
>
>
> Or just drop the _optional, and let your vbus controls operate on the
> dummy regulator you get back.
yes will do this. thanks for the suggestion and the review!
>
> (Right now vbus can't be NULL, so these checks are not very useful)
>
>> + if (IS_ERR(priv->vbus))
>> + return PTR_ERR(priv->vbus);
>> +
>> + return 0;
>
> return PTR_ERR_OR_ZERO(priv->vbus)
>
> (Although that might change based on above comment)
>
>> +}
>
> Regards,
> Bjorn
>
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