> From: Matthijs Kooijman [mailto:matthijs@xxxxxxxx] > Sent: Wednesday, May 15, 2013 11:48 AM > > > Paul wrote: > > > Hmm. Is it kosher to override these in a driver and force DMA to be > > > enabled? > > > > Apparently, since a lot of drivers do it like this. This particular code > > was taken from the ehci-platform driver. See also: > > > > http://thread.gmane.org/gmane.linux.usb.general/86066 > > > > The discussion in that thread suggests that even though this is not > > quite the optimal way to do this, it is the accepted way for now and > > changing it needs a bit more complicated changes and more discussion, > > apparently. > > > > > What if it has been disabled earlier on purpose, say because the > > > platform does not have DMA support? You say "This still allows any > > > platform code to set any more specific mask if needed", but how would > > > that be done exactly? > > Platform code could go over the list of platform devices and (based on the > > device-tree compatible value, for example) change the mask of a device. > > Admittedly, this could set a more specific mask, but not exactly disable > > dma entirely. I guess this is not a usecase for the other drivers? > > > > For the dwc2 driver, I guess the dwc2 hardware would not have dma > > enabled if the system does not support it anyway? > > > > Note that this code only runs for platform devices, so not for pci > > devices, which can disable dma by not setting a dma_mask when combined > > with the next patch. > Does this satisfy your doubts, or do you think further changes are > needed to this series of patches? No, seems like other folks think it's OK, so I'm fine with it. I'll ack the patches and send them on once Greg starts taking staging patches again. -- Paul -- 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
