[PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

[PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

[Yuan Fang]

It's more safe to set PHY ready after soft reset done

Let's consider a test case like this:
I have a usb PHY which don't need SW initial before access
it, But i have a wrong PHY clock default setting in PHY
register which means PHY is not ready in fact.
in dwc3_core_init, dwc3_core_get_phy will return 0 despite
usb get PHYs with return -ENODEV, and set phys_ready=true
but at this point, we can not say phys is ready or at least
it not safe to do that.
then, go on with dwc3_core_soft_reset,dwc3 reset core and
PHY, as phy->init is NULL in this case, so, usb_phy_init
do nothing and go on with a while loop which cost 1000*
20 ms, and return with -ETIMEDOUT
check phys_ready is set to TRUE but actually not.
Move phys_ready after soft reset done is more reasonable
and don't see side-effect yet.

Signed-off-by: Yuan Fang <yuan.fang@verisilicon.com>
---

Hi,
	please take a look at issue description above and kindly
	review this CL if any side-effect, many thanks.

B.R
Yuan Fang

 drivers/usb/dwc3/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index b6e53d8212cd..04b1bbaf694a 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -324,6 +324,7 @@ static int dwc3_core_soft_reset(struct dwc3 *dwc)
 	if (DWC3_VER_IS_WITHIN(DWC31, ANY, 180A))
 		msleep(50);
 
+	dwc->phys_ready = true;
 	return 0;
 }
 
@@ -979,7 +980,6 @@ static int dwc3_core_init(struct dwc3 *dwc)
 		ret = dwc3_core_get_phy(dwc);
 		if (ret)
 			goto err0a;
-		dwc->phys_ready = true;
 	}
 
 	ret = dwc3_core_soft_reset(dwc);
-- 
2.17.1

Re: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

[Greg KH]

On Fri, Jun 11, 2021 at 03:18:05PM +0800, Yuan Fang wrote:
> It's more safe to set PHY ready after soft reset done
> 
> Let's consider a test case like this:
> I have a usb PHY which don't need SW initial before access
> it, But i have a wrong PHY clock default setting in PHY
> register which means PHY is not ready in fact.
> in dwc3_core_init, dwc3_core_get_phy will return 0 despite
> usb get PHYs with return -ENODEV, and set phys_ready=true
> but at this point, we can not say phys is ready or at least
> it not safe to do that.
> then, go on with dwc3_core_soft_reset,dwc3 reset core and
> PHY, as phy->init is NULL in this case, so, usb_phy_init
> do nothing and go on with a while loop which cost 1000*
> 20 ms, and return with -ETIMEDOUT
> check phys_ready is set to TRUE but actually not.
> Move phys_ready after soft reset done is more reasonable
> and don't see side-effect yet.
> 
> Signed-off-by: Yuan Fang <yuan.fang@verisilicon.com>

What commit does this "fix"?  Should it also be backported to older
kernels?  If so, how far back?

thanks,

greg k-h

答复: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

[Fang, Yuan]

Hi Maintainer,

 Thanks so much for the quick reply.
 I would like to back ported to older kernels, but I can not
 figure out to which version is suitable, I can have a check later
 But merge into the new release version is also acceptable as I think.
 Thanks again.

B.R
Yuan Fang

-----邮件原件-----
发件人: Greg KH [mailto:gregkh@linuxfoundation.org] 
发送时间: 2021年6月11日 15:26
收件人: Yuan Fang
抄送: linux-usb@vger.kernel.org; balbi@kernel.org; Fang, Yuan
主题: Re: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

On Fri, Jun 11, 2021 at 03:18:05PM +0800, Yuan Fang wrote:
> It's more safe to set PHY ready after soft reset done
> 
> Let's consider a test case like this:
> I have a usb PHY which don't need SW initial before access it, But i 
> have a wrong PHY clock default setting in PHY register which means PHY 
> is not ready in fact.
> in dwc3_core_init, dwc3_core_get_phy will return 0 despite usb get 
> PHYs with return -ENODEV, and set phys_ready=true but at this point, 
> we can not say phys is ready or at least it not safe to do that.
> then, go on with dwc3_core_soft_reset,dwc3 reset core and PHY, as 
> phy->init is NULL in this case, so, usb_phy_init do nothing and go on 
> with a while loop which cost 1000*
> 20 ms, and return with -ETIMEDOUT
> check phys_ready is set to TRUE but actually not.
> Move phys_ready after soft reset done is more reasonable and don't see 
> side-effect yet.
> 
> Signed-off-by: Yuan Fang <yuan.fang@verisilicon.com>

What commit does this "fix"?  Should it also be backported to older kernels?  If so, how far back?

thanks,

greg k-h

Re: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 577 bytes --]

Yuan Fang <fangyuanseu@gmail.com> writes:

> It's more safe to set PHY ready after soft reset done
>
> Let's consider a test case like this:
> I have a usb PHY which don't need SW initial before access
> it, But i have a wrong PHY clock default setting in PHY
> register which means PHY is not ready in fact.
> in dwc3_core_init, dwc3_core_get_phy will return 0 despite
> usb get PHYs with return -ENODEV, and set phys_ready=true

your PHY driver shouldn't return -ENODEV here. Why are you returning
-ENODEV? The PHY isn't ready but it _does_ exist.

-- 
balbi

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 511 bytes --]

答复: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

[Fang, Yuan]

Hi Balbi,

> It's more safe to set PHY ready after soft reset done
>
> Let's consider a test case like this:
> I have a usb PHY which don't need SW initial before access it, But i 
> have a wrong PHY clock default setting in PHY register which means PHY 
> is not ready in fact.
> in dwc3_core_init, dwc3_core_get_phy will return 0 despite usb get 
> PHYs with return -ENODEV, and set phys_ready=true

> your PHY driver shouldn't return -ENODEV here. Why are you returning -ENODEV? The PHY isn't ready but it _does_ exist.

Sorry for the late reply, my explain may be not clear, let me describe it once more
1, I don’t coding a PHY driver, I have a PHY which do NOT need SW operation
All I should do is set the related PHY ctrl regs correctly. So I do not return anything to generic PHY framework.
2, In my above case, dwc3_core_get_phy will return 0, and set dwc->phys_ready=true, And then,
dwc3_core_soft_reset will cost retries*20ms to check if soft-reset is done , and return -ETIMEDOUT if time out, is that correct?

My point is, in this case(PHY do not set correctly, which is not rare during development stage I think), 
PHY initial fail led to soft-reset timeout but dwc->phys_ready is true,
So I think is more safe to say "PHY is ready" after soft-reset done, please let me know your opinion, thanks a lot

Yuan Fang
 
-----邮件原件-----
发件人: Felipe Balbi [mailto:balbi@kernel.org] 
发送时间: 2021年6月11日 21:03
收件人: Yuan Fang; linux-usb@vger.kernel.org
抄送: Fang, Yuan
主题: Re: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

Yuan Fang <fangyuanseu@gmail.com> writes:

> It's more safe to set PHY ready after soft reset done
>
> Let's consider a test case like this:
> I have a usb PHY which don't need SW initial before access it, But i 
> have a wrong PHY clock default setting in PHY register which means PHY 
> is not ready in fact.
> in dwc3_core_init, dwc3_core_get_phy will return 0 despite usb get 
> PHYs with return -ENODEV, and set phys_ready=true

your PHY driver shouldn't return -ENODEV here. Why are you returning -ENODEV? The PHY isn't ready but it _does_ exist.

--
balbi

答复: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

[Fang, Yuan]

Hi Maintainner,

Could you please share your thoughts with me?
Thanks a lot.


-----邮件原件-----
发件人: Fang, Yuan 
发送时间: 2021年6月16日 10:56
收件人: 'Felipe Balbi'; Yuan Fang; linux-usb@vger.kernel.org
主题: 答复: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

Hi Balbi,

> It's more safe to set PHY ready after soft reset done
>
> Let's consider a test case like this:
> I have a usb PHY which don't need SW initial before access it, But i 
> have a wrong PHY clock default setting in PHY register which means PHY 
> is not ready in fact.
> in dwc3_core_init, dwc3_core_get_phy will return 0 despite usb get 
> PHYs with return -ENODEV, and set phys_ready=true

> your PHY driver shouldn't return -ENODEV here. Why are you returning -ENODEV? The PHY isn't ready but it _does_ exist.

Sorry for the late reply, my explain may be not clear, let me describe it once more 1, I don’t coding a PHY driver, I have a PHY which do NOT need SW operation All I should do is set the related PHY ctrl regs correctly. So I do not return anything to generic PHY framework.
2, In my above case, dwc3_core_get_phy will return 0, and set dwc->phys_ready=true, And then, dwc3_core_soft_reset will cost retries*20ms to check if soft-reset is done , and return -ETIMEDOUT if time out, is that correct?

My point is, in this case(PHY do not set correctly, which is not rare during development stage I think), PHY initial fail led to soft-reset timeout but dwc->phys_ready is true, So I think is more safe to say "PHY is ready" after soft-reset done, please let me know your opinion, thanks a lot

Yuan Fang
 
-----邮件原件-----
发件人: Felipe Balbi [mailto:balbi@kernel.org]
发送时间: 2021年6月11日 21:03
收件人: Yuan Fang; linux-usb@vger.kernel.org
抄送: Fang, Yuan
主题: Re: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

Yuan Fang <fangyuanseu@gmail.com> writes:

> It's more safe to set PHY ready after soft reset done
>
> Let's consider a test case like this:
> I have a usb PHY which don't need SW initial before access it, But i 
> have a wrong PHY clock default setting in PHY register which means PHY 
> is not ready in fact.
> in dwc3_core_init, dwc3_core_get_phy will return 0 despite usb get 
> PHYs with return -ENODEV, and set phys_ready=true

your PHY driver shouldn't return -ENODEV here. Why are you returning -ENODEV? The PHY isn't ready but it _does_ exist.

--
balbi

答复: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

[Fang, Yuan]

Hi Maintainer,

May I know your thoughts on this topic?
Thanks a lot.


-----邮件原件-----
发件人: Fang, Yuan 
发送时间: 2021年6月29日 10:42
收件人: Fang, Yuan; 'Felipe Balbi'; 'Yuan Fang'; 'linux-usb@vger.kernel.org'
主题: 答复: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

Hi Maintainner,

Could you please share your thoughts with me?
Thanks a lot.


-----邮件原件-----
发件人: Fang, Yuan
发送时间: 2021年6月16日 10:56
收件人: 'Felipe Balbi'; Yuan Fang; linux-usb@vger.kernel.org
主题: 答复: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

Hi Balbi,

> It's more safe to set PHY ready after soft reset done
>
> Let's consider a test case like this:
> I have a usb PHY which don't need SW initial before access it, But i 
> have a wrong PHY clock default setting in PHY register which means PHY 
> is not ready in fact.
> in dwc3_core_init, dwc3_core_get_phy will return 0 despite usb get 
> PHYs with return -ENODEV, and set phys_ready=true

> your PHY driver shouldn't return -ENODEV here. Why are you returning -ENODEV? The PHY isn't ready but it _does_ exist.

Sorry for the late reply, my explain may be not clear, let me describe it once more 1, I don’t coding a PHY driver, I have a PHY which do NOT need SW operation All I should do is set the related PHY ctrl regs correctly. So I do not return anything to generic PHY framework.
2, In my above case, dwc3_core_get_phy will return 0, and set dwc->phys_ready=true, And then, dwc3_core_soft_reset will cost retries*20ms to check if soft-reset is done , and return -ETIMEDOUT if time out, is that correct?

My point is, in this case(PHY do not set correctly, which is not rare during development stage I think), PHY initial fail led to soft-reset timeout but dwc->phys_ready is true, So I think is more safe to say "PHY is ready" after soft-reset done, please let me know your opinion, thanks a lot

Yuan Fang
 
-----邮件原件-----
发件人: Felipe Balbi [mailto:balbi@kernel.org]
发送时间: 2021年6月11日 21:03
收件人: Yuan Fang; linux-usb@vger.kernel.org
抄送: Fang, Yuan
主题: Re: [PATCH] drivers/usb/dwc3: Set PHY ready after soft reset done

Yuan Fang <fangyuanseu@gmail.com> writes:

> It's more safe to set PHY ready after soft reset done
>
> Let's consider a test case like this:
> I have a usb PHY which don't need SW initial before access it, But i 
> have a wrong PHY clock default setting in PHY register which means PHY 
> is not ready in fact.
> in dwc3_core_init, dwc3_core_get_phy will return 0 despite usb get 
> PHYs with return -ENODEV, and set phys_ready=true

your PHY driver shouldn't return -ENODEV here. Why are you returning -ENODEV? The PHY isn't ready but it _does_ exist.

--
balbi