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
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