Re: [PATCH 1/1] mfd: omap-usb-host: Fix USB device detection problemson OMAP4 Panda

From: Roger Quadros
Date: Mon Dec 02 2013 - 07:06:17 EST

Michael,

On 12/02/2013 11:51 AM, Michael Trimarchi wrote:
> Hi Roger
>
> On Mon, Dec 2, 2013 at 10:39 AM, Roger Quadros <rogerq@xxxxxx> wrote:
>> +Benoit, Tony, Paul.
>>
>> Hi Michael,
>>
>> On 11/30/2013 06:48 AM, Michael Trimarchi wrote:
>>> Hi Roger
>>>
>>> On Fri, Nov 29, 2013 at 2:01 PM, Roger Quadros <rogerq@xxxxxx> wrote:
>>>> With u-boot 2013.10, USB devices are sometimes not detected
>>>> on OMAP4 Panda. To make us independent of what bootloader does
>>>> with the USB Host module, we must RESET it to get it to a known
>>>> good state. This patch Soft RESETs the USB Host module.
>>>>
>>>> Reported-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
>>>> Cc: <stable@xxxxxxxxxxxxxxx> # 3.10+
>>>> Signed-off-by: Roger Quadros <rogerq@xxxxxx>
>>>> ---
>>>> drivers/mfd/omap-usb-host.c | 115 +++++++++++++++++++++++++++++++++++++++++---
>>>> 1 file changed, 109 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/drivers/mfd/omap-usb-host.c b/drivers/mfd/omap-usb-host.c
>>>> index 142650f..d4bd464 100644
>>>> --- a/drivers/mfd/omap-usb-host.c
>>>> +++ b/drivers/mfd/omap-usb-host.c
>>>> @@ -43,14 +43,18 @@
>>>> /* UHH Register Set */
>>>> #define OMAP_UHH_REVISION (0x00)
>>>> #define OMAP_UHH_SYSCONFIG (0x10)
>>>> -#define OMAP_UHH_SYSCONFIG_MIDLEMODE (1 << 12)
>>>> +#define OMAP_UHH_SYSCONFIG_MIDLEMASK (3 << 12)
>>>> +#define OMAP_UHH_SYSCONFIG_MIDLESHIFT (12)
>>>> #define OMAP_UHH_SYSCONFIG_CACTIVITY (1 << 8)
>>>> -#define OMAP_UHH_SYSCONFIG_SIDLEMODE (1 << 3)
>>>> +#define OMAP_UHH_SYSCONFIG_SIDLEMASK (3 << 3)
>>>> +#define OMAP_UHH_SYSCONFIG_SIDLESHIFT (3)
>>>> #define OMAP_UHH_SYSCONFIG_ENAWAKEUP (1 << 2)
>>>> #define OMAP_UHH_SYSCONFIG_SOFTRESET (1 << 1)
>>>> #define OMAP_UHH_SYSCONFIG_AUTOIDLE (1 << 0)
>>>>
>>>> #define OMAP_UHH_SYSSTATUS (0x14)
>>>> +#define OMAP_UHH_SYSSTATUS_RESETDONE (1 << 0)
>>>> +
>>>> #define OMAP_UHH_HOSTCONFIG (0x40)
>>>> #define OMAP_UHH_HOSTCONFIG_ULPI_BYPASS (1 << 0)
>>>> #define OMAP_UHH_HOSTCONFIG_ULPI_P1_BYPASS (1 << 0)
>>>> @@ -66,10 +70,10 @@
>>>> #define OMAP4_UHH_HOSTCONFIG_APP_START_CLK (1 << 31)
>>>>
>>>> /* OMAP4-specific defines */
>>>> -#define OMAP4_UHH_SYSCONFIG_IDLEMODE_CLEAR (3 << 2)
>>>> -#define OMAP4_UHH_SYSCONFIG_NOIDLE (1 << 2)
>>>> -#define OMAP4_UHH_SYSCONFIG_STDBYMODE_CLEAR (3 << 4)
>>>> -#define OMAP4_UHH_SYSCONFIG_NOSTDBY (1 << 4)
>>>> +#define OMAP4_UHH_SYSCONFIG_MIDLEMASK (3 << 2)
>>>> +#define OMAP4_UHH_SYSCONFIG_MIDLESHIFT (2)
>>>> +#define OMAP4_UHH_SYSCONFIG_SIDLEMASK (3 << 4)
>>>> +#define OMAP4_UHH_SYSCONFIG_SIDLESHIFT (4)
>>>> #define OMAP4_UHH_SYSCONFIG_SOFTRESET (1 << 0)
>>>>
>>>> #define OMAP4_P1_MODE_CLEAR (3 << 16)
>>>> @@ -81,6 +85,12 @@
>>>>
>>>> #define OMAP_UHH_DEBUG_CSR (0x44)
>>>>
>>>> +/* MIDLE modes */
>>>> +#define OMAP_UHH_SYSCONFIG_MIDLE_NOSTANDBY (1)
>>>> +
>>>> +/* SIDLE modes */
>>>> +#define OMAP_UHH_SYSCONFIG_SIDLE_NOIDLE (1)
>>>> +
>>>> /* Values of UHH_REVISION - Note: these are not given in the TRM */
>>>> #define OMAP_USBHS_REV1 0x00000010 /* OMAP3 */
>>>> #define OMAP_USBHS_REV2 0x50700100 /* OMAP4 */
>>>> @@ -474,6 +484,97 @@ static unsigned omap_usbhs_rev2_hostconfig(struct usbhs_hcd_omap *omap,
>>>> return reg;
>>>> }
>>>>
>>>
>>> I'm digging in the code but as I understand this should be done by
>>> omap_hwmod and
>>> i660 avoid reset of the ehci module. This is done by ocp_softreset?
>>>
>>
>> It won't be done by omap_hwmod as we set HWMOD_INIT_NO_RESET flag in the hwmod data [1].
>>
>> Question is do we do it in the driver of leave it to hwmod?
>>
>> The other concern about i660 is in this comment [1]
>>
>
> I don't find any description of this errata for omap4. Is this errata valid?

I can't say for sure. You might have to try it out without those flags and see if it works
reliably.

>
> My change was to remove the NO_INIT and add 2uS as you have done

The 2uS delay that I added was my mistake and I don't think it is required.
Just removing HWMOD_INIT_NO_RESET should work.

cheers,
-roger

>
>> /*
>> * During system oot; If the hwmod framework resets the module
>> * the module will have smart idle settings; which can lead to deadlock
>> * (above Errata Id:i660); so, dont reset the module during boot;
>> * Use HWMOD_INIT_NO_RESET.
>> */
>>
>> But if you look at the errata document [2], Advisory 1.108, it doesn't say that we can't be in smart-idle, but
>> only that we should put the module in force-idle, before cutting the module's functional clock. It also states
>> that the only way to recover from a lockup condition is to soft reset the module. So I'm not sure if the above comment
>> in the code is really valid. What if the lockup happens in the bootloader? In that case we will have to reset the module in
>> the kernel.
>
> Michael
>
>>
>> Doing the reset in probe does solve a problem for now i.e. eliminates dependency on bootloader.
>>
>> [1] - http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c#n2024
>> [2] - http://www.ti.com/litv/pdf/sprz318e
>>

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