From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Rini Date: Mon, 2 Mar 2020 14:59:12 -0500 Subject: [PATCH] usb: ehci: Fix "EHCI timed out on TD - token=XXXX" error on ehci-hcd In-Reply-To: <1ab0e8c5-8738-cd25-402f-f9f00c6bd29a@denx.de> References: <20200226112955.7930-1-lukma@denx.de> <20200302142150.7538c268@jawa> <20200302195428.GD18302@bill-the-cat> <1ab0e8c5-8738-cd25-402f-f9f00c6bd29a@denx.de> Message-ID: <20200302195912.GE18302@bill-the-cat> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Mon, Mar 02, 2020 at 08:58:26PM +0100, Marek Vasut wrote: > On 3/2/20 8:54 PM, Tom Rini wrote: > > On Mon, Mar 02, 2020 at 08:19:22PM +0100, Marek Vasut wrote: > >> On 3/2/20 2:21 PM, Lukasz Majewski wrote: > >>> Hi, > >> > >> Hi, > >> > >>>> This patch aims to improve robustness of 'usb' command operation on > >>>> the ehci-hcd IP block as it ports to contemporary U-Boot the patch > >>>> described and provided in [1] (originally applicable to U-Boot > >>>> 2016.05). > >>>> > >>>> According to the fix author - "rayvt" (from [1]): > >>>> > >>>> TD stands for "Queue Element Transfer Descriptor (qTD)", which is a > >>>> micro-code instruction for the EHCI USB chip. > >>>> The "token" field is detailed information, control, and status of the > >>>> TD's data transfer. In particular, the rightmost byte is the status > >>>> field. 0x80 bit means the TD is active and the data transfer has not > >>>> yet completed. 0x08 bit means there was some sort of data transfer > >>>> error (XactErr). > >>> ^^^^^^^ - this error is NOT handled now in mainline u-boot. Do > >>> you have any experience with it? > >> > >> No, but then I also didn't run into those yet. > >> > >>>> If the drive gets a transfer error, it refuses to do any other I/O > >>>> transfer until the error is properly cleared and reset. U-boot did > >>>> not do this, so every subsequent disk read would get a timeout error > >>>> because the drive would not send any data. The fix is to properly > >>>> clear and reset the USB disk when it gets a transfer error. > >> > >> So basically, what this says is, "we crashed the drive, because the > >> drive suffered counter overflow, thus we fix it by resetting the drive". > >> No, the fix is to not crash the drive in the first place. > >> > >>>> Every read operation starts at the maximum block size. When the USB > >>>> pendrive is not able to correctly serve this data read request, the > >>>> dynamic reduction of IO size is performed. Up to six tries (with > >>>> smaller IO block each time) are attempted. > >>>> > >>>> A related problem is that some drives are slow to come up. Linux > >>>> handles this by issuing a spinup command and allowing more time for > >>>> the drive to respond. The same idea is applied in this fix. > >>>> > >>>> On TPC70 (i.MX6Q) once per ~10 times (without this patch): > >>>> > >>>> Bus usb at 2184200: USB EHCI 1.00 > >>>> scanning bus usb at 2184200 for devices... 2 USB Device(s) found > >>>> scanning usb for storage devices... 1 Storage Device(s) found > >>>> EHCI timed out on TD - token=0x1f8c80 > >>> > >>> This is how the error gets evident. The detailed explanation is in link > >>> [1]. > >> > >> Is there one specific post in that forum, or do I need to read through > >> the whole multi-page thread ? > >> > >> I would expect that if you run -- I assume 'usb reset' (the command is > >> missing above) -- then the bus gets power-cycled, hence the USB device > >> also gets power-cycled. > > > > FWIW, the problem I have does not get fixed via "usb reset". Ethernet > > never shows up again. I do see right now that I disabled network tests > > on the platform a long while ago for unknown reasons, but did comment to > > myself elsewhere that network was fairly flaky in U-Boot. > > There certainly is something with USB ethernet in U-Boot. I noticed the > flakiness myself, but didn't have time to investigate. Patches welcome I > guess ? Looking forward to testing them! -- Tom -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 659 bytes Desc: not available URL: