Re: [PATCH 1/2] usb: dwc2: Option to disable dma descriptor mode

On Tue, 2014-05-06 at 19:39 +0400, Sergei Shtylyov wrote:

Hello.

On 05/06/2014 02:23 AM, dinguyen-EIB2kfCEclfQT0dZR+AlfA@public.gmane.org wrote:

quoted

From: Dinh Nguyen <redacted>

quoted

Even though the IP supports Descriptor DMA mode, it does not support SPLIT
transactions in this mode. Since the driver can get the Descriptor DMA mode
support from hardware, the driver in its currently form cannot fully support
LS/FS devices connected to a HS Hub when Descriptor DMA mode is enabled in the
driver. Thus, we give the option to disable Descriptor DMA from device tree.

quoted

Signed-off-by: Dinh Nguyen <redacted>
---
  drivers/usb/dwc2/platform.c |    3 +++
  1 file changed, 3 insertions(+)

quoted

diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index eaba547..cb2133c 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c

@@ -123,6 +123,7 @@ static int dwc2_driver_probe(struct platform_device *dev)
  	struct resource *res;
  	int retval;
  	int irq;
+	u32 prop;

  	if (usb_disabled())
  		return -ENODEV;

@@ -135,6 +136,8 @@ static int dwc2_driver_probe(struct platform_device *dev)
  		dwc2_set_all_params(&defparams, -1);
  		params = &defparams;
  	}
+	if (!of_property_read_u32(dev->dev.of_node, "dma-desc-enable", &prop))
+		defparams.dma_desc_enable = prop;

    You don't really need a helper local variable here, the variable receiving 
the property value won't be changed if there was an error retrieving it.

Ah yes, you're right. Thanks for the review.

Dinh

WBR, Sergei

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