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

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Date:   Wed, 11 Jan 2017 17:26:18 -0700
From:   Shuah Khan <shuahkh@....samsung.com>
To:     balbi@...nel.org, gregkh@...uxfoundation.org, arnd@...db.de
Cc:     Shuah Khan <shuahkh@....samsung.com>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] usb: dwc3-exynos Fix dma_mask WARN_ON from xhci_plat_probe()

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;
 
 	dwc->xhci = xhci;
 
-- 
2.7.4