Re: [PATCH v5 02/11] phy: exynos-ufs: add UFS PHY driver for EXYNOS SoC

[Kishon Vijay Abraham I <kishon-l0cyMroinI0@public.gmane.org>]

Hi,

On Tuesday 28 February 2017 01:51 PM, Alim Akhtar wrote:
> Hi Kishon,
> 
> On 02/28/2017 09:04 AM, Kishon Vijay Abraham I wrote:
>> Hi,
>>
>> On Monday 27 February 2017 07:40 PM, Alim Akhtar wrote:
>>> Hi Kishon,
>>>
>>> On 02/27/2017 10:56 AM, Kishon Vijay Abraham I wrote:
>>>> Hi,
>>>>
>>>> On Thursday 23 February 2017 12:20 AM, Alim Akhtar wrote:
>>>>> On Fri, Feb 3, 2017 at 2:49 PM, Alim Akhtar <alim.akhtar-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> 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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>>>>>>>>>
>>>>>>>>>> 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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>>>>>>>>> Signed-off-by: Alim Akhtar <alim.akhtar-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
>>>>>>>>>> Cc: Kishon Vijay Abraham I <kishon-l0cyMroinI0@public.gmane.org>
>>>>>>>>>> ---
>>>>>>>>>>   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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>>>>>>>>> + *
>>>>>>>>>> + * 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:
>>>>
>>>> Agree, there are quite a few users that require calibration of phy parameters.
>>>> I think previously it was accommodated in phy_init, hence it was not merged.
>>> Ok, thanks for this information.
>>>
>>>>>>  * 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.
>>>>
>>>> Not sure how you plan to use priv here?
>>>>
>>>  From ufs driver I am populating PHY _priv_ data and calling phy_calibrate()
>>>
>>> e.g
>>> ----------------------- from ufs-exynos.c
>>> Instead of using below code earlier
>>> - exynos_ufs_phy_calibrate(generic_phy,CFG_PRE_INIT,PWR_MODE_ANY);
>>>
>>> Now I am using below from ufs-exynos driver
>>>
>>> + generic_phy->priv =(void*)CFG_PRE_INIT;
>>> + phy_calibrate(generic_phy);
>>>
>>> and in drivers/phy/phy-exynos-ufs.c
>>> using phy->priv in calibration function.
>>
>> Don't prefer passing of such private pointers between drivers. Why is this needed?
>>
> As already explained before, this is needed to pass the calibration 
> point (when you want to do the calibration?, like before init, after 
> init or before/after _mode_ change etc).
> 
> I Don't think we have much option here, if we want to make 
> phy_calibration generic enough.
> 
> We have few options:
> 1> One way is to have phy_calibration takes some argument like 
> calibration point (which was part of  my v3~v5), but looking at the 
> current implementation of phy-qcom-ufs.c, this approach might not be 
> generic enough.
> 
> 2> And using EXPORT_SYMBOL way is not encourage (as in my V1, even 
> though others in phy drivers uses it).
> 
> 3> the current proposal of using _priv_ data.
> 
> Out of the above 3 option, I feel using _priv_ data is more generic way 
> (and most of the major sub-system in Linux uses it).
> 
> lets see what other people think about __priv__ approach.
> 
> Please suggest your prefer way to handle this.

Generally calibration has to be done at a single point. Having to do
calibration in multiple places seems to be specific to Exynos.

Can implementing a small state machine in exynos driver help?

Thanks
Kishon
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