linux-kernel - [PATCH] usb: dwc3: core: leave default DMA if the controller does not support 64-bit DMA

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Date:   Thu,  1 Sep 2022 16:34:46 +0800
From:   William Wu <william.wu@...k-chips.com>
To:     balbi@...nel.org, gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        william.wu@...k-chips.com, fabioaiuto83@...il.com,
        sven@...npeter.dev, frank.wang@...k-chips.com,
        jianwei.zheng@...k-chips.com
Subject: [PATCH] usb: dwc3: core: leave default DMA if the controller does not support 64-bit DMA

On some DWC3 controllers (e.g. Rockchip SoCs), the DWC3 core
doesn't support 64-bit DMA address width. In this case, this
driver should use the default 32-bit mask. Otherwise, the DWC3
controller will break if it runs on above 4GB physical memory
environment.

This patch reads the DWC_USB3_AWIDTH bits of GHWPARAMS0 which
used for the DMA address width, and only configure 64-bit DMA
mask if the DWC_USB3_AWIDTH is 64.

Fixes: 45d39448b4d0 ("usb: dwc3: support 64 bit DMA in platform driver")
Signed-off-by: William Wu <william.wu@...k-chips.com>
---
 drivers/usb/dwc3/core.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index c5c238ab3083..2fcbd05b2af1 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1751,12 +1751,6 @@ static int dwc3_probe(struct platform_device *pdev)
 
 	dwc3_get_properties(dwc);
 
-	if (!dwc->sysdev_is_parent) {
-		ret = dma_set_mask_and_coherent(dwc->sysdev, DMA_BIT_MASK(64));
-		if (ret)
-			return ret;
-	}
-
 	dwc->reset = devm_reset_control_array_get_optional_shared(dev);
 	if (IS_ERR(dwc->reset))
 		return PTR_ERR(dwc->reset);
@@ -1823,6 +1817,13 @@ static int dwc3_probe(struct platform_device *pdev)
 	dwc3_cache_hwparams(dwc);
 	device_init_wakeup(&pdev->dev, of_property_read_bool(dev->of_node, "wakeup-source"));
 
+	if (!dwc->sysdev_is_parent &&
+	    DWC3_GHWPARAMS0_AWIDTH(dwc->hwparams.hwparams0) == 64) {
+		ret = dma_set_mask_and_coherent(dwc->sysdev, DMA_BIT_MASK(64));
+		if (ret)
+			goto disable_clks;
+	}
+
 	spin_lock_init(&dwc->lock);
 	mutex_init(&dwc->mutex);
 
-- 
2.34.1