Em Fri, 17 Mar 2017 10:24:15 +0900 Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> escreveu: > On Thu, Mar 16, 2017 at 09:08:40PM -0300, Mauro Carvalho Chehab wrote: > > The dwc2 hardware doesn't like to do DMA transfers without > > aligning data in DWORD. The driver also assumes that, even > > when there's no DMA, at dwc2_read_packet(). > > > > That cause buffer overflows, preventing some drivers to work. > > Why aren't the drivers being fixed? This is a well-known (hopefully) > restriction on USB data buffers, can't the uvc_driver be fixed? I talked to Laurent about on IRC. He told that he is willing to consider that option, if the USB API explicitly states that all buffers must be dword-aligned (and/or buffer sizes). IMHO, he has a point: if this is a restriction of for usb transfer buffers, it should be documented somewhere. Yet, a quick check with: $ git grep -i dword Documentation/usb/ $ git grep -i align Documentation/usb/ Didn't hit anything related to it. > > In the specific case of uvc_driver, it uses an array where > > it caches the content of video controls, passing it to the > > USB stack via usb_control_msg(). Typical controls use 1 or 2 > > bytes. The net result is that other values of the buffer > > gets overriden when this function is called. > > Not good, it should be fixed, otherwise you are going to have to try to > fix up all host controllers :( > > thanks, > > greg k-h Thanks, Mauro -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
