Date:   Thu, 9 Sep 2021 19:28:49 +0200
From:   Andre Muller <andre.muller@....de>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Saravana Kannan <saravanak@...gle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [Bisected Regression] OLPC XO-1.5: Internal drive and SD card
 (mmcblk*) gone since commit ea718c699055

On 09/09/2021 17.14, Rob Herring wrote:
> On Thu, Sep 9, 2021 at 9:09 AM Andre Muller <andre.muller@....de> wrote:
>>
>> On 09/09/2021 00.31, Rob Herring wrote:
>>> On Tue, Sep 7, 2021 at 10:15 PM Saravana Kannan <saravanak@...gle.com> wrote:
>>>>
>>>> On Tue, Sep 7, 2021 at 7:12 PM Andre Muller <andre.muller@....de> wrote:
>>>>>
>>>>> On 08/09/2021 00.05, Saravana Kannan wrote:
>>>>>> On Sun, Sep 5, 2021 at 1:15 AM Andre Muller <andre.muller@....de> wrote:
>>>>>>>
>>>>>>> With linux-5.13 and linux-5.14, the internal drive and SD card reader are gone from the XO-1.5. I bisected the issue to come up with ea718c699055:
>>>>>>>
>>>>>>> # first bad commit: [ea718c699055c8566eb64432388a04974c43b2ea] Revert "Revert "driver core: Set fw_devlink=on by default""
>>>>>>>
>>>>>>> The /dev/mmcblk* nodes are not generated since this patch.
>>>>>>>
>>>>>>> Please find the output of lspsi -vv and lshw below.
>>>>>>>
>>>>>>> I will be happy to provide more info and/or test patches.
>>>>>>
>>>>>> Hi Andre,
>>>>>>
>>>>>> Can you point me to the dts file in upstream that corresponds to this system?
>>>>>>
>>>>>> Also, if you can give the output of:
>>>>>> cat /sys/kernel/debug/devices_deferred
>>>>>
>>>>> Hi Saravana,
>>>>>
>>>>>
>>>>> /sys/kernel/debug/devices_deferred is empty.
>>>>> I used the last good commit b6f617.
>>>>
>>>> Sorry, I wanted that with the bad commit.
>>
>> Uh-oh, my bad...
>>
>> The bad case says
>> # cat devices_deferred
>> 0000:00:0c.0
>>
>> That's the SD Host controller.
>>
>>>>
>>>>>
>>>>> The XO-1.5 has an x86 compatible VIA C7 processor.
>>>>> It uses the VX855 chip for about all I/O tasks, including SDIO.
>>>>> I am not aware of a device tree file for it.
>>>>>
>>>>> It is a bit of a strange beast, it uses OFW to initialize the hardware and provide a FORTH shell.
>>>>> Which also is the boot manager, configured via FORTH scripts.
>>>>>
>>>>>    From the linux side of the fence, dmesg's line 2 is:
>>>>>
>>>>> "OFW detected in memory, cif @ 0xff83ae68 (reserving top 8MB)"
>>>>>
>>>>> AIUI, this mechanism is used in lieu of a device tree file, like UEFI on most x86 hardware.
>>>>> But my understanding of device trees is severely limited, I might be allwrong.
>>>>
>>>> Uhh... I'm so confused. If Linux doesn't use OF, then none of the code
>>>> enabled by fw_devlink=on should be executed.
>>>
>>> Linux does, but maybe not for memory (like UEFI on arm64).
>>>
>>>> The only thing that might remotely even execute is:
>>>> efifb_add_links() in drivers/firmware/efi/efi-init.c
>>>>
>>>> If you want you can just do an early return 0; in that to see if it
>>>> makes a difference (unlikely).
>>>>
>>>> Rob, Do you know what's going on with OLPC and DT?
>>>
>>> Not really. I have an XO-1 DT dump[1]. It's probably a similar looking
>>> DT though. It's pretty ancient lacking anything we've invented for DT
>>> in the last 10 years. There's not really much to it as about the only
>>> phandle I see is for interrupts.
>>>
>>>>> Anyway, the firmware source is here:
>>>>> http://dev.laptop.org/git/users/quozl/openfirmware/
>>>>>
>>>>> This file is the closest dt-analogous thing for the XO-1.5 I can find therein:
>>>>> cpu/x86/pc/olpc/via/devices.fth
>>>>
>>>> That file is all gibberish to me.
>>>
>>> Running this on a booted system would help:
>>>
>>> dtc -f -I fs -O dts /proc/device-tree > dump.dts
>>
>> Ah, thanks. I never knew about the DT in there...
>> XO-1.5_dump.dts is attached.
>>
>>>
>>> If you don't have dtc on the system, then you'll have to zip up
>>> /proc/device-tree contents and run dtc elsewhere (or just post that).
>>>
>>>>> My machine runs the latest version:
>>>>> http://wiki.laptop.org/go/OLPC_Firmware_q3c17
>>>>>
>>>>> The XO-1.5 hardware specs are here:
>>>>> http://wiki.laptop.org/images/f/f0/CL1B_Hdwe_Design_Spec.pdf
>>>>> http://wiki.laptop.org/go/Hardware_specification_1.5
>>>>>
>>>>> Would the .config or dmesg help?
>>>>
>>>> At this point, why not? When you do send them, please send them as
>>>> attachments and not inline.
>>>>
>>>> Also, when you collect the dmesg logs, the following could help:
>>>> Enable the existing dev_dbg logs in these functions:
>>>> device_link_add()
>>>> device_links_check_suppliers()
>>>>
>>>> And add the following log to fwnode_link_add():
>>>> +++ b/drivers/base/core.c
>>>> @@ -87,6 +87,8 @@ int fwnode_link_add(struct fwnode_handle *con,
>>>> struct fwnode_handle *sup)
>>>>                   goto out;
>>>>           }
>>>>
>>>> +       pr_info("Link fwnode %pfwP as a consumer of fwnode %pfwP\n", con, sup);
>>>> +
>>>
>>
>> OK. The dmesg with debug info is attached as well (for the broken case).
>
> Humm, ACPI and DT together...
>
> Looks to me like it's waiting for the wrong interrupt-parent. The log
> says it is waiting for 'interrupt-controller@...' which is the only
> interrupt-controller found in the DT, but the parent is the PCI bridge
> with whatever interrupt-map is pointing to. That's not clear as the
> phandle (0x767a4) doesn't exist in the DT. I suppose the parent is
> defined in ACPI?

FWIW, I attached an acpidump of the XO-1.5.
Also I prepared a dmesg for the previous, working commit, with minimal noise for diff-ing.

Hope that helps,
Andre

>
> If there's not an easy fix, just disable devlinks for x86. There's
> only one other DT platform, ce4100, and I really doubt it is even used
> at all.
>
> Rob
>


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