On 07/27/2009 04:17 PM, Daniel J Blueman wrote:
With DMA debugging enabled, I see a warning when the FTDI USB-serial driver loads [1] using a non-DMAable address. I can get a disassembly of some of the stack frames to identify the exact call-sites etc, if that helps anyone? Thanks, Daniel --- [1] usbcore: registered new interface driver usbserial_generic usbserial: USB Serial Driver core USB Serial support registered for FTDI USB Serial Device ftdi_sio 5-1:1.0: FTDI USB Serial Device converter detected usb 5-1: Detected FT8U232AM usb 5-1: Number of endpoints 2 usb 5-1: Endpoint 1 MaxPacketSize 64 usb 5-1: Endpoint 2 MaxPacketSize 64 usb 5-1: Setting MaxPacketSize 64 ------------[ cut here ]------------ WARNING: at lib/dma-debug.c:856 check_for_stack+0x9a/0xc0() Hardware name: OEM uhci_hcd 0000:00:1d.0: DMA-API: device driver maps memory from stack [addr=ffff88007f89b946]
Looks like some of the functions in ftdi_sio.c call usb_control_msg with a stack buffer and some use a kmalloc buffer. They should likely all be using a kmalloc buffer.
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