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

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 <redacted>

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

thanks,

greg k-h