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From: Marek Vasut <marex@denx.de>
To: u-boot@lists.denx.de
Subject: [PATCH] usb: dwc2: Add small delay after reset
Date: Mon, 23 Dec 2019 12:58:44 +0100	[thread overview]
Message-ID: <097cb601-6ff5-0a95-0af0-58998fdaa867@denx.de> (raw)
In-Reply-To: <1577088452-3684-1-git-send-email-ley.foon.tan@intel.com>

On 12/23/19 9:07 AM, Ley Foon Tan wrote:
> In Cyclone 5 SoC platform, the first USB probing is failed but second
> probing is success. DWC2 driver read gsnpsid register right after de-assert
> reset, but controller is not ready yet and it returns gsnpsid 0.
> Adding small delay after de-assert reset solve the issue.
> 
> Retry with this fix more than 10 times without issue.
> 
> => usb reset
> resetting USB...
> Bus usb at ffb40000: usb probe
> SNPSID invalid (not DWC2 OTG device): 00000000
> Port not available.
> => usb reset
> resetting USB...
> Bus usb at ffb40000: usb probe
> scanning bus usb at ffb40000 for devices... 2 USB Device(s) found
>        scanning usb for storage devices... 1 Storage Device(s) found

Can't you poll for the readiness of the IP somehow instead of using
arbitrary delay ?

  reply	other threads:[~2019-12-23 11:58 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-23  8:07 [PATCH] usb: dwc2: Add small delay after reset Ley Foon Tan
2019-12-23 11:58 ` Marek Vasut [this message]
2019-12-24  2:00   ` Tan, Ley Foon

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