Re: [PATCH V9 13/15] phy: tegra: Add PCIe PIPE2UPHY support

[Vidya Sagar <vidyas@nvidia.com>]

On 6/10/2019 5:24 PM, Dmitry Osipenko wrote:
> 07.06.2019 17:46, Vidya Sagar пишет:
>> Synopsys DesignWare core based PCIe controllers in Tegra 194 SoC interface
>> with Universal PHY (UPHY) module through a PIPE2UPHY (P2U) module.
>> For each PCIe lane of a controller, there is a P2U unit instantiated at
>> hardware level. This driver provides support for the programming required
>> for each P2U that is going to be used for a PCIe controller.
>>
>> Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
>> ---
>> Changes since [v8]:
>> * Made it dependent on ARCH_TEGRA_194_SOC directly instead of ARCH_TEGRA
>>
>> Changes since [v7]:
>> * Changed P2U driver file name from pcie-p2u-tegra194.c to phy-tegra194-p2u.c
>>
>> Changes since [v6]:
>> * None
>>
>> Changes since [v5]:
>> * Addressed review comments from Thierry
>>
>> Changes since [v4]:
>> * None
>>
>> Changes since [v3]:
>> * Rebased on top of linux-next top of the tree
>>
>> Changes since [v2]:
>> * Replaced spaces with tabs in Kconfig file
>> * Sorted header file inclusion alphabetically
>>
>> Changes since [v1]:
>> * Added COMPILE_TEST in Kconfig
>> * Removed empty phy_ops implementations
>> * Modified code according to DT documentation file modifications
>>
>>   drivers/phy/tegra/Kconfig            |   7 ++
>>   drivers/phy/tegra/Makefile           |   1 +
>>   drivers/phy/tegra/phy-tegra194-p2u.c | 109 +++++++++++++++++++++++++++
>>   3 files changed, 117 insertions(+)
>>   create mode 100644 drivers/phy/tegra/phy-tegra194-p2u.c
>>
>> diff --git a/drivers/phy/tegra/Kconfig b/drivers/phy/tegra/Kconfig
>> index e516967d695b..f9817c3ae85f 100644
>> --- a/drivers/phy/tegra/Kconfig
>> +++ b/drivers/phy/tegra/Kconfig
>> @@ -7,3 +7,10 @@ config PHY_TEGRA_XUSB
>>   
>>   	  To compile this driver as a module, choose M here: the module will
>>   	  be called phy-tegra-xusb.
>> +
>> +config PHY_TEGRA194_P2U
>> +	tristate "NVIDIA Tegra194 PIPE2UPHY PHY driver"
>> +	depends on ARCH_TEGRA_194_SOC || COMPILE_TEST
>> +	select GENERIC_PHY
>> +	help
>> +	  Enable this to support the P2U (PIPE to UPHY) that is part of Tegra 19x SOCs.
>> diff --git a/drivers/phy/tegra/Makefile b/drivers/phy/tegra/Makefile
>> index 64ccaeacb631..320dd389f34d 100644
>> --- a/drivers/phy/tegra/Makefile
>> +++ b/drivers/phy/tegra/Makefile
>> @@ -6,3 +6,4 @@ phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_124_SOC) += xusb-tegra124.o
>>   phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_132_SOC) += xusb-tegra124.o
>>   phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_210_SOC) += xusb-tegra210.o
>>   phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_186_SOC) += xusb-tegra186.o
>> +obj-$(CONFIG_PHY_TEGRA194_P2U) += phy-tegra194-p2u.o
>> diff --git a/drivers/phy/tegra/phy-tegra194-p2u.c b/drivers/phy/tegra/phy-tegra194-p2u.c
>> new file mode 100644
>> index 000000000000..7b84b4c55e43
>> --- /dev/null
>> +++ b/drivers/phy/tegra/phy-tegra194-p2u.c
>> @@ -0,0 +1,109 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * P2U (PIPE to UPHY) driver for Tegra T194 SoC
>> + *
>> + * Copyright (C) 2019 NVIDIA Corporation.
>> + *
>> + * Author: Vidya Sagar <vidyas@nvidia.com>
>> + */
>> +
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/phy/phy.h>
>> +
>> +#define P2U_PERIODIC_EQ_CTRL_GEN3	0xc0
>> +#define P2U_PERIODIC_EQ_CTRL_GEN3_PERIODIC_EQ_EN		BIT(0)
>> +#define P2U_PERIODIC_EQ_CTRL_GEN3_INIT_PRESET_EQ_TRAIN_EN	BIT(1)
>> +#define P2U_PERIODIC_EQ_CTRL_GEN4	0xc4
>> +#define P2U_PERIODIC_EQ_CTRL_GEN4_INIT_PRESET_EQ_TRAIN_EN	BIT(1)
>> +
>> +#define P2U_RX_DEBOUNCE_TIME				0xa4
>> +#define P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_MASK	0xffff
>> +#define P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_VAL		160
>> +
>> +struct tegra_p2u {
>> +	void __iomem *base;
>> +};
>> +
>> +static int tegra_p2u_power_on(struct phy *x)
>> +{
>> +	struct tegra_p2u *phy = phy_get_drvdata(x);
>> +	u32 val;
>> +
>> +	val = readl(phy->base + P2U_PERIODIC_EQ_CTRL_GEN3);
>> +	val &= ~P2U_PERIODIC_EQ_CTRL_GEN3_PERIODIC_EQ_EN;
>> +	val |= P2U_PERIODIC_EQ_CTRL_GEN3_INIT_PRESET_EQ_TRAIN_EN;
>> +	writel(val, phy->base + P2U_PERIODIC_EQ_CTRL_GEN3);
>> +
>> +	val = readl(phy->base + P2U_PERIODIC_EQ_CTRL_GEN4);
>> +	val |= P2U_PERIODIC_EQ_CTRL_GEN4_INIT_PRESET_EQ_TRAIN_EN;
>> +	writel(val, phy->base + P2U_PERIODIC_EQ_CTRL_GEN4);
>> +
>> +	val = readl(phy->base + P2U_RX_DEBOUNCE_TIME);
>> +	val &= ~P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_MASK;
>> +	val |= P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_VAL;
>> +	writel(val, phy->base + P2U_RX_DEBOUNCE_TIME);
> 
> I'm wondering whether you're really need to insert memory barriers for
> each readl/writel, can't the relaxed versions be used instead?
Well, there is no real need to use readl/writel with their memory barriers.
I'll push new series replacing them with their _relaxed() counterparts.

> 
> The same applies to other patches as well.
>