Re: [PATCH 2/2] remoteproc: core: Add fixed memory region support

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Fri 26 Aug 13:19 PDT 2016, Loic Pallardy wrote:

> Some coprocessors request fixed memory mapping for firmware execution
> and associated communication linked.
> Memory resources are defined in firmware resource table.
> Resource address different from 0x0 and 0xFFFFFFFF is considered as predefined

Do you think we're required to support both 0 and -1 for this?

> and already reserved at system level.
> In that case, remoteproc core doesn't need to perform any allocation.
> Memory region access can be managed using memremap/memunmap functions
> 
> Signed-off-by: Loic Pallardy <loic.pallardy@st.com>
> ---
>  drivers/remoteproc/remoteproc_core.c | 61 ++++++++++++++++++++++++++----------
>  include/linux/remoteproc.h           |  4 +++
>  2 files changed, 49 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 18f4286..0ddbb92 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -213,13 +213,25 @@ int rproc_alloc_vring(struct rproc_vdev *rvdev, int i)
>  	/* actual size of vring (in bytes) */
>  	size = PAGE_ALIGN(vring_size(rvring->len, rvring->align));
>  
> -	/*
> -	 * Allocate non-cacheable memory for the vring. In the future
> -	 * this call will also configure the IOMMU for us
> -	 */
> -	va = dma_alloc_coherent(dev->parent, size, &dma, GFP_KERNEL);
> +	rsc = (void *)rproc->table_ptr + rvdev->rsc_offset;
> +
> +	/* check if specific memory region requested by firmware */
> +	if (rsc->vring[i].da != 0 && rsc->vring[i].da != FW_RSC_ADDR_ANY) {

I think we should convert that reserved field in the vring to a "pa";
allowing this resource to not be 1:1 mapped into the remote. And if
nothing else just to be consistent with the carveouts and devmem.


@Suman, do you have any input on this?

Regards,
Bjorn