Re: [PATCH v3 09/24] wfx: add hwio.c/hwio.h

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tue, Dec 22, 2020 at 05:10:11PM +0200, Kalle Valo wrote:
> Jerome Pouiller <Jerome.Pouiller@xxxxxxxxxx> writes:
> 
> > +/*
> > + * Internal helpers.
> > + *
> > + * About CONFIG_VMAP_STACK:
> > + * When CONFIG_VMAP_STACK is enabled, it is not possible to run DMA on stack
> > + * allocated data. Functions below that work with registers (aka functions
> > + * ending with "32") automatically reallocate buffers with kmalloc. However,
> > + * functions that work with arbitrary length buffers let's caller to handle
> > + * memory location. In doubt, enable CONFIG_DEBUG_SG to detect badly located
> > + * buffer.
> > + */
> 
> This sounds very hacky to me, I have understood that you should never
> use stack with DMA.

You should never do that because some platforms do not support it, so no
driver should ever try to do that as they do not know what platform they
are running on.

thanks,

greg k-h



[Index of Archives]     [Linux Memonry Technology]     [Linux USB Devel]     [Linux Media]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux