[U-Boot] chiliSOM: USB bug

Wed Apr 11 16:08:09 UTC 2018

Hi Witold,

On 11.04.2018 08:18, sdrb wrote:
> Hi,
> 
> I use Grinn's chiliSOM and very old U-boot 2014.07 on it. Unfortunately 
> the newest u-boot doesn't run SPL properly - so I'm forced to use 
> 2014.07 version.

What are your problems exactly with SPL? What version of chiliSOM does
you board have? Mainline u-boot with SPL runs successfully on
chiliboard 1.1 (containing chiliSOM 2.2).

> 
> I noticed that there is some problem with USB maintenance. As far as I 
> know the chiliSOM is TI AM335x compatible system so it uses Mentor USB 
> OTG controller.
> 
> The problem occures when I'm trying to use following sequence of commands:
> 
> # usb start
> # usb stop
> # usb start

See output of commands issued on u-boot 2018.03:

=> usb start
starting USB...
USB0:   scanning bus 0 for devices... 1 USB Device(s) found
        scanning usb for storage devices... Device NOT ready
    Request Sense returned 02 3A 00
Device NOT ready
    Request Sense returned 02 3A 00
Device NOT ready
    Request Sense returned 02 3A 00
Device NOT ready
    Request Sense returned 02 3A 00
0 Storage Device(s) found
=> usb stop
stopping USB..
=> usb start
starting USB...
USB0:   scanning bus 0 for devices... 1 USB Device(s) found
        scanning usb for storage devices... Device NOT ready
    Request Sense returned 02 3A 00
Device NOT ready
    Request Sense returned 02 3A 00
Device NOT ready
    Request Sense returned 02 3A 00
Device NOT ready
    Request Sense returned 02 3A 00
0 Storage Device(s) found

Did you try to connect other USB devices? Is that issue connected
USB device dependent?

Regards,
Marcin

> 
> and after the second "usb start" I get error:
> 
> [2018-04-06 08:13:42.600] U-Boot# usb start
> [2018-04-06 08:13:44.162] (Re)start USB...
> [2018-04-06 08:13:44.164] USB0:   scanning bus 0 for devices... 5 USB 
> Device(s) found
> [2018-04-06 08:13:50.872]        scanning usb for storage devices... 0 
> Storage Device(s) found
> [2018-04-06 08:13:50.881] U-Boot# usb stop
> [2018-04-06 08:13:55.514] stopping USB..
> [2018-04-06 08:13:55.521] U-Boot# usb start
> [2018-04-06 08:14:01.962] (Re)start USB...
> [2018-04-06 08:14:01.964] USB0:   lowlevel init failed
> [2018-04-06 08:14:16.730] USB error: all controllers failed lowlevel init
> [2018-04-06 08:14:16.734] U-Boot#
> 
> I dig a little the code and I noticed that there is some line which 
> breaks up things.
> The problem is in proc musb_generic_disable() where there is zeroed 
> DEVCTL register.
> Seems like zeroing breaks somehow Mentor USB because after it it not 
> possible to turn USB host mode.
> 
> I tried to solve the problem with push MUSB into suspend mode, then zero 
> DEVCTL and then resume MUSB, but still no success.
> So I decided to remove this line from my code and now it seems to work. 
> I mean now USB is working fine:
> 
> [2018-04-06 08:15:44.290] U-Boot# usb start
> [2018-04-06 08:15:45.787] (Re)start USB...
> [2018-04-06 08:15:45.790] USB0:   scanning bus 0 for devices... 5 USB 
> Device(s) found
> [2018-04-06 08:15:52.489]        scanning usb for storage devices... 0 
> Storage Device(s) found
> [2018-04-06 08:15:52.495] U-Boot# usb stop
> [2018-04-06 08:15:54.835] stopping USB..
> [2018-04-06 08:15:54.837] U-Boot# usb start
> [2018-04-06 08:17:03.323] (Re)start USB...
> [2018-04-06 08:17:03.325] USB0:   scanning bus 0 for devices... 5 USB 
> Device(s) found
> [2018-04-06 08:17:09.864]        scanning usb for storage devices... 0 
> Storage Device(s) found
> [2018-04-06 08:17:09.871] U-Boot#
> 
> 
> I know that my u-boot version 2014.07 is quite old, but the proc 
> musb_generic_disable() in newest version is the same so probably the 
> problem also still occures on other boards.
> 
> Anyone can verify or confirm that? I'd like to know if this is not 
> specific to my board with chiliSOM.
> I removed zeroing of DEVCTL register but maybe there is some better 
> solution?
> 
> Any thoughts?
> 
> WK
> 
> 
> commit 22447924ca27d3332698d3976f3e5e653bf893cc
> Author: Witold Kowolik <sdrb at onet.eu>
> Date:   Wed Apr 11 07:49:42 2018 +0200
> 
>      ARM: am335x: chiliSOM: Temporary workaround for Mentor OTG USB in 
> host mode
> 
>      Signed-off-by: Witold Kowolik <sdrb at onet.eu>
> 
> diff --git a/drivers/usb/musb-new/musb_core.c 
> b/drivers/usb/musb-new/musb_core.c
> index 79e118ef85..2be2bd6081 100644
> --- a/drivers/usb/musb-new/musb_core.c
> +++ b/drivers/usb/musb-new/musb_core.c
> @@ -977,7 +977,7 @@ static void musb_generic_disable(struct musb *musb)
>       musb_writew(mbase, MUSB_INTRRXE, 0);
> 
>       /* off */
> -    musb_writeb(mbase, MUSB_DEVCTL, 0);
> +    /* musb_writeb(mbase, MUSB_DEVCTL, 0); */
> 
>       /*  flush pending interrupts */
>       temp = musb_readb(mbase, MUSB_INTRUSB);
> 
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-- 
Marcin Niestroj