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Message-ID: <26099de1-826f-42bf-0de7-759a47faf4a0@samsung.com>
Date: Wed, 4 Aug 2021 13:29:31 +0200
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"linux-samsung-soc@...r.kernel.org"
<linux-samsung-soc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc: Artur Petrosyan <Arthur.Petrosyan@...opsys.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
Krzysztof Kozlowski <krzk@...nel.org>
Subject: Re: [PATCH] usb: dwc2: Skip clock gating on Samsung SoCs
Hi
On 03.08.2021 12:08, Minas Harutyunyan wrote:
> On 8/3/2021 1:40 PM, Marek Szyprowski wrote:
>> On 16.07.2021 16:54, Minas Harutyunyan wrote:
>>> On 7/16/2021 9:01 AM, Marek Szyprowski wrote:
>>>> Commit 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr
>>>> function.") changed the way the driver handles power down modes in a such
>>>> way that it uses clock gating when no other power down mode is available.
>>>>
>>>> This however doesn't work well on the DWC2 implementation used on the
>>>> Samsung SoCs. When a clock gating is enabled, system hangs. It looks that
>>>> the proper clock gating requires some additional glue code in the shared
>>>> USB2 PHY and/or Samsung glue code for the DWC2. To restore driver
>>>> operation on the Samsung SoCs simply skip enabling clock gating mode
>>>> until one finds what is really needed to make it working reliably.
>>>>
>>>> Fixes: 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")
>>>> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
>>>> ---
>>>> drivers/usb/dwc2/core.h | 4 ++++
>>>> drivers/usb/dwc2/core_intr.c | 3 ++-
>>>> drivers/usb/dwc2/hcd.c | 6 ++++--
>>>> drivers/usb/dwc2/params.c | 1 +
>>>> 4 files changed, 11 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
>>>> index ab6b815e0089..483de2bbfaab 100644
>>>> --- a/drivers/usb/dwc2/core.h
>>>> +++ b/drivers/usb/dwc2/core.h
>>>> @@ -383,6 +383,9 @@ enum dwc2_ep0_state {
>>>> * 0 - No (default)
>>>> * 1 - Partial power down
>>>> * 2 - Hibernation
>>>> + * @no_clock_gating: Specifies whether to avoid clock gating feature.
>>>> + * 0 - No (use clock gating)
>>>> + * 1 - Yes (avoid it)
>>>> * @lpm: Enable LPM support.
>>>> * 0 - No
>>>> * 1 - Yes
>>>> @@ -480,6 +483,7 @@ struct dwc2_core_params {
>>>> #define DWC2_POWER_DOWN_PARAM_NONE 0
>>>> #define DWC2_POWER_DOWN_PARAM_PARTIAL 1
>>>> #define DWC2_POWER_DOWN_PARAM_HIBERNATION 2
>>>> + bool no_clock_gating;
>>>>
>>>> bool lpm;
>>>> bool lpm_clock_gating;
>>>> diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
>>>> index a5ab03808da6..a5c52b237e72 100644
>>>> --- a/drivers/usb/dwc2/core_intr.c
>>>> +++ b/drivers/usb/dwc2/core_intr.c
>>>> @@ -556,7 +556,8 @@ static void dwc2_handle_usb_suspend_intr(struct dwc2_hsotg *hsotg)
>>>> * If neither hibernation nor partial power down are supported,
>>>> * clock gating is used to save power.
>>>> */
>>>> - dwc2_gadget_enter_clock_gating(hsotg);
>>>> + if (!hsotg->params.no_clock_gating)
>>>> + dwc2_gadget_enter_clock_gating(hsotg);
>>>> }
>>>>
>>>> /*
>>>> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
>>>> index 035d4911a3c3..2a7828971d05 100644
>>>> --- a/drivers/usb/dwc2/hcd.c
>>>> +++ b/drivers/usb/dwc2/hcd.c
>>>> @@ -3338,7 +3338,8 @@ int dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
>>>> * If not hibernation nor partial power down are supported,
>>>> * clock gating is used to save power.
>>>> */
>>>> - dwc2_host_enter_clock_gating(hsotg);
>>>> + if (!hsotg->params.no_clock_gating)
>>>> + dwc2_host_enter_clock_gating(hsotg);
>>>> break;
>>>> }
>>>>
>>>> @@ -4402,7 +4403,8 @@ static int _dwc2_hcd_suspend(struct usb_hcd *hcd)
>>>> * If not hibernation nor partial power down are supported,
>>>> * clock gating is used to save power.
>>>> */
>>>> - dwc2_host_enter_clock_gating(hsotg);
>>>> + if (!hsotg->params.no_clock_gating)
>>>> + dwc2_host_enter_clock_gating(hsotg);
>>>>
>>>> /* After entering suspend, hardware is not accessible */
>>>> clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
>>>> diff --git a/drivers/usb/dwc2/params.c b/drivers/usb/dwc2/params.c
>>>> index 67c5eb140232..59e119345994 100644
>>>> --- a/drivers/usb/dwc2/params.c
>>>> +++ b/drivers/usb/dwc2/params.c
>>>> @@ -76,6 +76,7 @@ static void dwc2_set_s3c6400_params(struct dwc2_hsotg *hsotg)
>>>> struct dwc2_core_params *p = &hsotg->params;
>>>>
>>>> p->power_down = DWC2_POWER_DOWN_PARAM_NONE;
>>>> + p->no_clock_gating = true;
>>>> p->phy_utmi_width = 8;
>>>> }
>>>>
>>>>
>>> In which mode host/device you see the issue?
>> I do my test in my device mode.
>>> What is your core version? Please provide GHWCFG1-4 registers values.
>> This is a result of dwc2_dump_global_registers() added just after
>> dwc2_lowlevel_hw_enable() in dwc2_driver_probe():
>>
>> dwc2 12480000.hsotg: Core Global Registers
>>
>> dwc2 12480000.hsotg: GOTGCTL @0xE0260000 : 0x000D0000
>> dwc2 12480000.hsotg: GOTGINT @0xE0260004 : 0x00000000
>> dwc2 12480000.hsotg: GAHBCFG @0xE0260008 : 0x00000027
>> dwc2 12480000.hsotg: GUSBCFG @0xE026000C : 0x0000540F
>> dwc2 12480000.hsotg: GRSTCTL @0xE0260010 : 0x80000040
>> dwc2 12480000.hsotg: GINTSTS @0xE0260014 : 0x54008428
>> dwc2 12480000.hsotg: GINTMSK @0xE0260018 : 0x800C3800
>> dwc2 12480000.hsotg: GRXSTSR @0xE026001C : 0x616EC77D
>> dwc2 12480000.hsotg: GRXFSIZ @0xE0260024 : 0x00000400
>> dwc2 12480000.hsotg: GNPTXFSIZ @0xE0260028 : 0x04000400
>> dwc2 12480000.hsotg: GNPTXSTS @0xE026002C : 0x00080400
>> dwc2 12480000.hsotg: GI2CCTL @0xE0260030 : 0x00000000
>> dwc2 12480000.hsotg: GPVNDCTL @0xE0260034 : 0x00000000
>> dwc2 12480000.hsotg: GGPIO @0xE0260038 : 0x00000000
>> dwc2 12480000.hsotg: GUID @0xE026003C : 0x00000000
>> dwc2 12480000.hsotg: GSNPSID @0xE0260040 : 0x4F54281A
>> dwc2 12480000.hsotg: GHWCFG1 @0xE0260044 : 0x00000000
>> dwc2 12480000.hsotg: GHWCFG2 @0xE0260048 : 0x228FFC50
>> dwc2 12480000.hsotg: GHWCFG3 @0xE026004C : 0x1E8084E8
>> dwc2 12480000.hsotg: GHWCFG4 @0xE0260050 : 0xFFF08030
>> dwc2 12480000.hsotg: GLPMCFG @0xE0260054 : 0x00000000
>> dwc2 12480000.hsotg: GPWRDN @0xE0260058 : 0x00000000
>> dwc2 12480000.hsotg: GDFIFOCFG @0xE026005C : 0x00000000
>> dwc2 12480000.hsotg: HPTXFSIZ @0xE0260100 : 0x00000000
>> dwc2 12480000.hsotg: PCGCTL @0xE0260E00 : 0x00000000
>> dwc2 12480000.hsotg: dwc2_check_params: Invalid parameter besl=1
>> dwc2 12480000.hsotg: dwc2_check_params: Invalid parameter
>> g_np_tx_fifo_size=1024
>> dwc2 12480000.hsotg: EPs: 16, dedicated fifos, 7808 entries in SPRAM
>>> Is the issue seen because of programming PCGCTL.PCGCTL_GATEHCLK bit
>>> only? To check it, could you please comment this bit setting/resetting
>>> in clock gating functions:
>>> dwc2_host_exit_clock_gating()
>>> dwc2_host_enter_clock_gating()
>>> dwc2_gadget_exit_clock_gating()
>>> dwc2_gadget_enter_clock_gating()
>> After removing programming PCGCTL.PCGCTL_GATEHCLK bit in the above
>> functions, everything works fine.
>>
>> Best regards
>>
> Thank you for testing and confirm my expectations.
>
> There are 3 options:
> 1. Do not update your patch and accept it
> 2. Update your patch to exclude programming of PCGCTL.PCGCTL_GATEHCLK
> bit based on hsotg->params.no_clock_gating in all
> ..._exit/enter_clock_gating functions
> 3. More radical solution, to have really ...POWER_DOWN_NONE case:
> - rename DWC2_POWER_DOWN_PARAM_NONE to DWC2_POWER_DOWN_CLOCK_GATING in
> whole driver;
> - define new power state "#define DWC2_POWER_DOWN_PARAM_NONE -1"
> - and for all platforms who doesn't want to have any power optimization
> keep:
> p->power_down = DWC2_POWER_DOWN_PARAM_NONE;
>
>
> I would prefer option 3. What you think about this solution? Can you
> implement it (I guess it required 5 min) and test on your platform.
Okay, I will do the 3rd option. However, the $subject patch has been
already merged to v5.14-rc3 some time ago, so I will do that on top of
v5.14-rc3.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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