linux-kernel - Re: [PATCH] usb: dwc3-exynos Fix dma_mask WARN_ON from xhci_plat

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Date:   Thu, 12 Jan 2017 09:35:00 -0700
From:   Shuah Khan <shuahkh@....samsung.com>
To:     Felipe Balbi <balbi@...nel.org>, gregkh@...uxfoundation.org,
        arnd@...db.de
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Shuah Khan <shuahkh@....samsung.com>
Subject: Re: [PATCH] usb: dwc3-exynos Fix dma_mask WARN_ON from
 xhci_plat_probe()

On 01/12/2017 12:26 AM, Felipe Balbi wrote:
> 
> Hi,
> 
> Shuah Khan <shuahkh@....samsung.com> writes:
>> During dwc3_exynos_probe(), WARN_ON(!pdev->dev.dma_mask) is triggered from
>> xhci_plat_probe(). dwc3_host_init() doesn't configure DMA prior to adding
>> the platform device.
>>
>> dwc3_host_init() was changed to not configure DMA with the change to use
>> bus->sysdev for DMA config.
>>
>> sysdev_is_parent is not true for dwc3-exynos. This might be the reason why
>> there is a need to configure DMA in dwc3_host_init() prior to adding the
>> platform device for xhci in this path.
>>
>> This fix adds the DMA config to dwc3_host_init() without undoing any other
>> changes in
>> commit d64ff406e51e ("usb: dwc3: use bus->sysdev for DMA configuration")
>>
>> [    3.372356] WARNING: CPU: 2 PID: 108 at drivers/usb/host/xhci-plat.c:168 xhc0
>> [    3.381381] Modules linked in:
>> [    3.384373] CPU: 2 PID: 108 Comm: kworker/2:1 Not tainted 4.10.0-rc2-00250-g8
>> [    3.392783] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
>> [    3.398854] Workqueue: events deferred_probe_work_func
>> [    3.403994] [<c010e19c>] (unwind_backtrace) from [<c010ae84>] (show_stack+0x)
>> [    3.411696] [<c010ae84>] (show_stack) from [<c0335d50>] (dump_stack+0x78/0x8)
>> [    3.418877] [<c0335d50>] (dump_stack) from [<c011aef8>] (__warn+0xe8/0x100)
>> [    3.425796] [<c011aef8>] (__warn) from [<c011afc0>] (warn_slowpath_null+0x20)
>> [    3.433344] [<c011afc0>] (warn_slowpath_null) from [<c04deb74>] (xhci_plat_p)
>> [    3.441845] [<c04deb74>] (xhci_plat_probe) from [<c041f1dc>] (platform_drv_p)
>> [    3.450157] [<c041f1dc>] (platform_drv_probe) from [<c041d848>] (driver_prob)
>> [    3.458994] [<c041d848>] (driver_probe_device) from [<c041bd78>] (bus_for_ea)
>> [    3.467485] [<c041bd78>] (bus_for_each_drv) from [<c041d538>] (__device_atta)
>> [    3.475716] [<c041d538>] (__device_attach) from [<c041cb70>] (bus_probe_devi)
>> [    3.483872] [<c041cb70>] (bus_probe_device) from [<c041af54>] (device_add+0x)
>> [    3.491741] [<c041af54>] (device_add) from [<c041ef4c>] (platform_device_add)
>> [    3.499892] [<c041ef4c>] (platform_device_add) from [<c04a5168>] (dwc3_host_)
>> [    3.508379] [<c04a5168>] (dwc3_host_init) from [<c04a4f64>] (dwc3_probe+0x94)
>> [    3.516091] [<c04a4f64>] (dwc3_probe) from [<c041f1dc>] (platform_drv_probe+)
>> [    3.523975] [<c041f1dc>] (platform_drv_probe) from [<c041d848>] (driver_prob)
>> [    3.532814] [<c041d848>] (driver_probe_device) from [<c041bd78>] (bus_for_ea)
>> [    3.541306] [<c041bd78>] (bus_for_each_drv) from [<c041d538>] (__device_atta)
>> [    3.549538] [<c041d538>] (__device_attach) from [<c041cb70>] (bus_probe_devi)
>> [    3.557684] [<c041cb70>] (bus_probe_device) from [<c041af54>] (device_add+0x)
>> [    3.565582] [<c041af54>] (device_add) from [<c0576334>] (of_platform_device_)
>> [    3.574586] [<c0576334>] (of_platform_device_create_pdata) from [<c0576464>])
>> [    3.584722] [<c0576464>] (of_platform_bus_create) from [<c05767d8>] (of_plat)
>> [    3.593828] [<c05767d8>] (of_platform_populate) from [<c04ab334>] (dwc3_exyn)
>> [    3.602660] [<c04ab334>] (dwc3_exynos_probe) from [<c041f1dc>] (platform_drv)
>> [    3.611150] [<c041f1dc>] (platform_drv_probe) from [<c041d848>] (driver_prob)
>> [    3.619988] [<c041d848>] (driver_probe_device) from [<c041bd78>] (bus_for_ea)
>> [    3.628480] [<c041bd78>] (bus_for_each_drv) from [<c041d538>] (__device_atta)
>> [    3.636712] [<c041d538>] (__device_attach) from [<c041cb70>] (bus_probe_devi)
>> [    3.644857] [<c041cb70>] (bus_probe_device) from [<c041d04c>] (deferred_prob)
>> [    3.653798] [<c041d04c>] (deferred_probe_work_func) from [<c0130c68>] (proce)
>>
>> Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
>> ---
>> Arnd! I isolated the smallest change to avoid the WARN_ON. Please let me
>> know if this problem could be fixed in another way.
>>
>>  drivers/usb/dwc3/host.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
>> index 487f0ff..f68f71f 100644
>> --- a/drivers/usb/dwc3/host.c
>> +++ b/drivers/usb/dwc3/host.c
>> @@ -84,7 +84,10 @@ int dwc3_host_init(struct dwc3 *dwc)
>>  		return -ENOMEM;
>>  	}
>>  
>> +	dma_set_coherent_mask(&xhci->dev, dwc->dev->coherent_dma_mask);
>>  	xhci->dev.parent	= dwc->dev;
>> +	xhci->dev.dma_mask      = dwc->dev->dma_mask;
>> +	xhci->dev.dma_parms     = dwc->dev->dma_parms;
> 
> this is the result of a missed patch. Mathias is discussing the proper
> fix for this.
> 

Can you please point me to the thread if you have it handy?

thanks,
-- Shuah