Messages in this thread | | | Subject | Re: [PATCH] usb: dwc3: core: leave default DMA if the controller does not support 64-bit DMA | From | wuliangfeng <> | Date | Sat, 3 Sep 2022 23:33:09 +0800 |
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On 2022/9/2 上午1:38, Sven Peter wrote: > > > On Thu, Sep 1, 2022, at 10:34, William Wu wrote: >> 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@rock-chips.com> > > Reviewed-by: Sven Peter <sven@svenpeter.dev> > >> --- >> 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; >> + } > > I guess you could also create the mask from DWC3_GHWPARAMS0_AWIDTH(dwc->hwparams.hwparams0) > directly instead of hardcoding it to 64bit here. Probably doesn't matter though unless > there are some weird systems where dwc3 can only do 48bit DMA but there's actually memory > above that. > > Refer to the DWC3 databook "Table 4-1 Basic Config Parameters", it describe that "If your system address bus width for example is 40bits, select 64 and tie the address bits[63:40] of the DWC3_usb3 to 0", so it seems that "DWC3_GHWPARAMS0_AWIDTH(dwc->hwparams.hwparams0) == 64" can cover 40-bit DMA or 48-bit DMA.
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