Message-ID: <CAGOxZ50gh_SErTiDbkjqNTCds-8ghgxXofSgzSwp6hicAcw23Q@mail.gmail.com>
Date:   Thu, 23 Feb 2017 00:20:43 +0530
From:   Alim Akhtar <alim.akhtar@...il.com>
To:     Alim Akhtar <alim.akhtar@...sung.com>
Cc:     Kishon Vijay Abraham I <kishon@...com>, linux-scsi@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "James E.J. Bottomley" <JBottomley@...n.com>,
        vinayak holikatti <vinholikatti@...il.com>,
        Vivek Gautam <gautam.vivek@...sung.com>,
        Seungwon Jeon <essuuj@...il.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Pankaj Dubey <pankaj.dubey@...sung.com>,
        vivek.gautam@...eaurora.org
Subject: Re: [PATCH v5 02/11] phy: exynos-ufs: add UFS PHY driver for EXYNOS SoC

On Fri, Feb 3, 2017 at 2:49 PM, Alim Akhtar <alim.akhtar@...sung.com> wrote:
> Hi Kishon,
>
>
> On 11/19/2015 07:09 PM, Kishon Vijay Abraham I wrote:
>>
>> Hi,
>>
>> On Tuesday 17 November 2015 01:41 PM, Alim Akhtar wrote:
>>>
>>> Hi
>>> Thanks again for looking into this.
>>>
>>> On 11/17/2015 11:46 AM, Kishon Vijay Abraham I wrote:
>>>>
>>>> Hi,
>>>>
>>>> On Monday 09 November 2015 10:56 AM, Alim Akhtar wrote:
>>>>>
>>>>> From: Seungwon Jeon <essuuj@...il.com>
>>>>>
>>>>> This patch introduces Exynos UFS PHY driver. This driver
>>>>> supports to deal with phy calibration and power control
>>>>> according to UFS host driver's behavior.
>>>>>
>>>>> Signed-off-by: Seungwon Jeon <essuuj@...il.com>
>>>>> Signed-off-by: Alim Akhtar <alim.akhtar@...sung.com>
>>>>> Cc: Kishon Vijay Abraham I <kishon@...com>
>>>>> ---
>>>>>   drivers/phy/Kconfig                |    7 ++
>>>>>   drivers/phy/Makefile               |    1 +
>>>>>   drivers/phy/phy-exynos-ufs.c       |  241
>>>>> ++++++++++++++++++++++++++++++++++++
>>>>>   drivers/phy/phy-exynos-ufs.h       |   85 +++++++++++++
>>>>>   drivers/phy/phy-exynos7-ufs.h      |   89 +++++++++++++
>>>>>   include/linux/phy/phy-exynos-ufs.h |   85 +++++++++++++
>>>>>   6 files changed, 508 insertions(+)
>>>>>   create mode 100644 drivers/phy/phy-exynos-ufs.c
>>>>>   create mode 100644 drivers/phy/phy-exynos-ufs.h
>>>>>   create mode 100644 drivers/phy/phy-exynos7-ufs.h
>>>>>   create mode 100644 include/linux/phy/phy-exynos-ufs.h
>>>>>
>>>>> diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
>>>>> index 7eb5859dd035..7d38a92e0297 100644
>>>>> --- a/drivers/phy/Kconfig
>>>>> +++ b/drivers/phy/Kconfig
>>>>> @@ -389,4 +389,11 @@ config PHY_CYGNUS_PCIE
>>>>>         Enable this to support the Broadcom Cygnus PCIe PHY.
>>>>>         If unsure, say N.
>>>>>
>>>>> +config PHY_EXYNOS_UFS
>>>>> +    tristate "EXYNOS SoC series UFS PHY driver"
>>>>> +    depends on OF && ARCH_EXYNOS || COMPILE_TEST
>>>>> +    select GENERIC_PHY
>>>>> +    help
>>>>> +      Support for UFS PHY on Samsung EXYNOS chipsets.
>>>>> +
>>>>>   endmenu
>>>>> diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
>>>>> index 075db1a81aa5..9bec4d1a89e1 100644
>>>>> --- a/drivers/phy/Makefile
>>>>> +++ b/drivers/phy/Makefile
>>>>> @@ -10,6 +10,7 @@ obj-$(CONFIG_ARMADA375_USBCLUSTER_PHY)    +=
>>>>> phy-armada375-usb2.o
>>>>>   obj-$(CONFIG_BCM_KONA_USB2_PHY)        += phy-bcm-kona-usb2.o
>>>>>   obj-$(CONFIG_PHY_EXYNOS_DP_VIDEO)    += phy-exynos-dp-video.o
>>>>>   obj-$(CONFIG_PHY_EXYNOS_MIPI_VIDEO)    += phy-exynos-mipi-video.o
>>>>> +obj-$(CONFIG_PHY_EXYNOS_UFS)    += phy-exynos-ufs.o
>>>>>   obj-$(CONFIG_PHY_LPC18XX_USB_OTG)    += phy-lpc18xx-usb-otg.o
>>>>>   obj-$(CONFIG_PHY_PXA_28NM_USB2)        += phy-pxa-28nm-usb2.o
>>>>>   obj-$(CONFIG_PHY_PXA_28NM_HSIC)        += phy-pxa-28nm-hsic.o
>>>>> diff --git a/drivers/phy/phy-exynos-ufs.c
>>>>> b/drivers/phy/phy-exynos-ufs.c
>>>>> new file mode 100644
>>>>> index 000000000000..cb1aeaa3d4eb
>>>>> --- /dev/null
>>>>> +++ b/drivers/phy/phy-exynos-ufs.c
>>>>> @@ -0,0 +1,241 @@
>>>>> +/*
>>>>> + * UFS PHY driver for Samsung EXYNOS SoC
>>>>> + *
>>>>> + * Copyright (C) 2015 Samsung Electronics Co., Ltd.
>>>>> + * Author: Seungwon Jeon <essuuj@...il.com>
>>>>> + *
>>>>> + * This program is free software; you can redistribute it and/or
>>>>> modify
>>>>> + * it under the terms of the GNU General Public License as published
>>>>> by
>>>>> + * the Free Software Foundation; either version 2 of the License, or
>>>>> + * (at your option) any later version.
>>>>> + */
>>>>> +#include <linux/clk.h>
>>>>> +#include <linux/delay.h>
>>>>> +#include <linux/err.h>
>>>>> +#include <linux/io.h>
>>>>> +#include <linux/iopoll.h>
>>>>> +#include <linux/mfd/syscon.h>
>>>>> +#include <linux/module.h>
>>>>> +#include <linux/of.h>
>>>>> +#include <linux/phy/phy.h>
>>>>> +#include <linux/phy/phy-exynos-ufs.h>
>>>>> +#include <linux/platform_device.h>
>>>>> +#include <linux/regmap.h>
>>>>> +
>>>>> +#include "phy-exynos-ufs.h"
>>>>> +
>>>>> +#define for_each_phy_lane(phy, i) \
>>>>> +    for (i = 0; i < (phy)->lane_cnt; i++)
>>>>> +#define for_each_phy_cfg(cfg) \
>>>>> +    for (; (cfg)->id; (cfg)++)
>>>>> +
>>>>> +#define PHY_DEF_LANE_CNT    1
>>>>> +
>>>>> +static void exynos_ufs_phy_config(struct exynos_ufs_phy *phy,
>>>>> +            const struct exynos_ufs_phy_cfg *cfg, u8 lane)
>>>>> +{
>>>>> +    enum {LANE_0, LANE_1}; /* lane index */
>>>>> +
>>>>> +    switch (lane) {
>>>>> +    case LANE_0:
>>>>> +        writel(cfg->val, (phy)->reg_pma + cfg->off_0);
>>>>> +        break;
>>>>> +    case LANE_1:
>>>>> +        if (cfg->id == PHY_TRSV_BLK)
>>>>> +            writel(cfg->val, (phy)->reg_pma + cfg->off_1);
>>>>> +        break;
>>>>> +    }
>>>>> +}
>>>>> +
>>>>> +static bool match_cfg_to_pwr_mode(u8 desc, u8 required_pwr)
>>>>> +{
>>>>> +    if (IS_PWR_MODE_ANY(desc))
>>>>> +        return true;
>>>>> +
>>>>> +    if (IS_PWR_MODE_HS(required_pwr) && IS_PWR_MODE_HS_ANY(desc))
>>>>> +        return true;
>>>>> +
>>>>> +    if (COMP_PWR_MODE(required_pwr, desc))
>>>>> +        return true;
>>>>> +
>>>>> +    if (COMP_PWR_MODE_MD(required_pwr, desc) &&
>>>>> +        COMP_PWR_MODE_GEAR(required_pwr, desc) &&
>>>>> +        COMP_PWR_MODE_SER(required_pwr, desc))
>>>>> +        return true;
>>>>> +
>>>>> +    return false;
>>>>> +}
>>>>> +
>>>>> +int exynos_ufs_phy_calibrate(struct phy *phy,
>>>>> +                    enum phy_cfg_tag tag, u8 pwr)
>>>>
>>>>
>>>> This is similar to the first version of your patch without
>>>> EXPORT_SYMBOL.
>>>>
>>>> I think you have to create a new generic PHY_OPS for calibrate PHY while
>>>> making
>>>> sure that it is as generic as possible (which means calibrate_phy
>>>> shouldn't
>>>> have tag and pwr arguments or a strong justification as to why those
>>>> arguments
>>>> are required in a generic API).
>>>
>>> I don't see the advantage to making this a generic phy_ops, this is
>>> exynos
>>> specific ufs-phy, please have a look at other implementations
>>
>>
>> only the implementation is specific to exynos. I've seen lot of other
>> vendors
>> want to do something like calibrate phy.
>>
>> So if we add something like (*calibrate)(struct phy *phy), then it can be
>> used
>> by others as well. Russell King also want to minimize the code to program
>> calibration settings. So it would be good to come up with a set of
>> standard
>> bindings like 'phy,tx-swing', 'phy,emphasis', 'phy,amplitude' etc.. to
>> program
>> these settings.
>>>
>>> drivers/phy/phy-qcom-ufs.c (which I belive mereged recently)
>>
>>
>> Thats why I hate when someone else merge PHY drivers :-( That driver can
>> as
>> well be in drivers/misc as it doesn't use PHY framework as it is supposed
>> to be
>> used. It just exports a dozen of API's to be used by controller drivers.
>> ick..
>>
>>> may be other vendors might come with there own implementation of phy.
>>
>>
>> right, it's all about providing the correct callback functions.
>>>
>>> I am using what is currently provided by the generic phy framework.
>>
>>
>> I think for your use case, what is currently provided in the PHY framework
>> is
>> not sufficient.
>>
> Its little over a year since last time we discuss about adding a generic
> calibration API. I can see in the past people tried adding *calibration* API
> [1] but not sure why [1] was not landed in mainline.
> Anyway now we have many users of phy_calibration API, like UFS, USB and may
> be PCIe, there is a real need to add this functionality. So, here is my
> approach:
>  * Along with [1], we can add a void *priv for handling device specific phy
> private data, and before calling phy_calibration() from phy consumer,
> phy->priv is populated with private data.
> This approach solves exynos-ufs-phy  calibration as well.
> please have a look on the snapshot below, if you are ok, will post a proper
> patch for this:
>
> [1]: https://patchwork.kernel.org/patch/4545941/
> ----

Ping!!!

> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
> index a268f4d..78cec14 100644
> --- a/drivers/phy/phy-core.c
> +++ b/drivers/phy/phy-core.c
> @@ -357,6 +357,26 @@ int phy_set_mode(struct phy *phy, enum phy_mode mode)
>  }
>  EXPORT_SYMBOL_GPL(phy_set_mode);
>
> +int phy_calibrate(struct phy *phy)
> +{
> +       int ret = -ENOTSUPP;
> +
> +       if(!phy || !phy->ops->calibrate)
> +               return 0;
> +
> +       mutex_lock(&phy->mutex);
> +       ret = phy->ops->calibrate(phy);
> +       if (ret < 0) {
> +               dev_err(&phy->dev, "phy calibration failed %d\n", ret);
> +               goto out;
> +       }
> +
> +out:
> +       mutex_unlock(&phy->mutex);
> +
> +       return ret;
> +}
> +
>  int phy_reset(struct phy *phy)
>  {
>         int ret;
> diff --git a/include/linux/phy/phy.h b/include/linux/phy/phy.h
> index 78bb0d7..ca3a6d4 100644
> --- a/include/linux/phy/phy.h
> +++ b/include/linux/phy/phy.h
> @@ -45,6 +45,7 @@ struct phy_ops {
>         int     (*power_on)(struct phy *phy);
>         int     (*power_off)(struct phy *phy);
>         int     (*set_mode)(struct phy *phy, enum phy_mode mode);
> +       int     (*calibrate)(struct phy *phy);
>         int     (*reset)(struct phy *phy);
>         struct module *owner;
>  };
> @@ -67,6 +68,7 @@ struct phy_attrs {
>   * @init_count: used to protect when the PHY is used by multiple consumers
>   * @power_count: used to protect when the PHY is used by multiple consumers
>   * @phy_attrs: used to specify PHY specific attributes
> + * @priv: used to specify PHY specific private data
>   */
>  struct phy {
>         struct device           dev;
> @@ -77,6 +79,7 @@ struct phy {
>         int                     power_count;
>         struct phy_attrs        attrs;
>         struct regulator        *pwr;
> +       void                    *priv;
>  };
>
>  /**
> @@ -138,6 +141,7 @@ int phy_exit(struct phy *phy);
>  int phy_power_on(struct phy *phy);
>  int phy_power_off(struct phy *phy);
>  int phy_set_mode(struct phy *phy, enum phy_mode mode);
> +int phy_calibrate(struct phy *phy);
>  int phy_reset(struct phy *phy);
>  static inline int phy_get_bus_width(struct phy *phy)
>  {
> @@ -253,6 +257,13 @@ static inline int phy_set_mode(struct phy *phy, enum
> phy_mode mode)
>         return -ENOSYS;
>  }
>
> +static inline int phy_calibrate(struct phy *phy)
> +{
> +       if (!phy)
> +               return 0;
> +       return -ENOSYS;
> +}
> +
>  static inline int phy_reset(struct phy *phy)
>  {
>         if (!phy)
>
>> Thanks
>> Kishon
>>
>>
>



-- 
Regards,
Alim

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