Hi,
On 11/13/2015 10:58 PM, Simon Glass wrote:
Hi Hans,
<snip>
Talking about usb-stop, there is still one (BIG!) problem after this patch set when building usb-support with DM_DEVICE_REMOVE not set. This means that the controllers dma engines will not be stopped when booting the actual OS and they will still be accessing parts of the main memory while the actual OS is booting, which is BAD. So I suggest adding something like this to all host drivers which use dma in this way:
#if defined CONFIG_DM_USB && !defined CONFIG_DM_DEVICE_REMOVE #error The EHCI driver cannot be used without CONFIG_DM_DEVICE_REMOVE otherwise DMA stays active while booting the OS #endif
Sounds good. I am not suggesting that we encourage people to build USB with out DM_DEVICE_REMOVE. I just want to make sure that we don't create unnecessary dependencies such that DM_DEVICE_REMOVE becomes impossible to use.
We have a note in the Kconfig for that, but I agree we need to make it more explicit. With the #if approach it makes the pitfall much more obvious.
Ack, so we need to have patches for this for at least ohci, ehci, xhci and I guess also uhci ? Who is going to write these patches ?
I suppose I could do that. I would like to make sure that any USB fish hooks are removed, and that is part of the solution.
I'd really like to resolve this and move things forward. If you still have have strong objections please let me know.
There are no objections from my side to move forward with your current solution.
We did discuss this at the time and I was clear that I did not want to keep the solution as it was - I merged it because it fixed a bug, as you pointed out at the time.
Ack.
Regards,
Hans