Re: [Linaro-mm-sig] Re: [PATCH v3] misc: sram: Add DMA-BUF Heap exporting of SRAM areas

[Christian König]

Am 13.07.23 um 21:28 schrieb Greg Kroah-Hartman:
> On Thu, Jul 13, 2023 at 02:13:16PM -0500, Andrew Davis wrote:
> > This new export type exposes to userspace the SRAM area as a DMA-BUF Heap,
> > this allows for allocations of DMA-BUFs that can be consumed by various
> > DMA-BUF supporting devices.
> What devices exactly?
>
> And what userspace tools/programs are going to use this api?
>
> > Signed-off-by: Andrew Davis <afd@xxxxxx>
> > ---
> >
> > Changes from v2:
> >   - Make sram_dma_heap_allocate static (kernel test robot)
> >   - Rebase on v6.5-rc1
> >
> >   drivers/misc/Kconfig         |   7 +
> >   drivers/misc/Makefile        |   1 +
> >   drivers/misc/sram-dma-heap.c | 245 +++++++++++++++++++++++++++++++++++
> >   drivers/misc/sram.c          |   6 +
> >   drivers/misc/sram.h          |  16 +++
> >   5 files changed, 275 insertions(+)
> >   create mode 100644 drivers/misc/sram-dma-heap.c
> >
> > diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> > index 75e427f124b28..ee34dfb61605f 100644
> > --- a/drivers/misc/Kconfig
> > +++ b/drivers/misc/Kconfig
> > @@ -448,6 +448,13 @@ config SRAM
> >   config SRAM_EXEC
> >   	bool
> >   
> > +config SRAM_DMA_HEAP
> > +	bool "Export on-chip SRAM pools using DMA-Heaps"
> > +	depends on DMABUF_HEAPS && SRAM
> > +	help
> > +	  This driver allows the export of on-chip SRAM marked as both pool
> > +	  and exportable to userspace using the DMA-Heaps interface.
> Module name?
>
> >   config DW_XDATA_PCIE
> >   	depends on PCI
> >   	tristate "Synopsys DesignWare xData PCIe driver"
> > diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> > index f2a4d1ff65d46..5e7516bfaa8de 100644
> > --- a/drivers/misc/Makefile
> > +++ b/drivers/misc/Makefile
> > @@ -47,6 +47,7 @@ obj-$(CONFIG_VMWARE_VMCI)	+= vmw_vmci/
> >   obj-$(CONFIG_LATTICE_ECP3_CONFIG)	+= lattice-ecp3-config.o
> >   obj-$(CONFIG_SRAM)		+= sram.o
> >   obj-$(CONFIG_SRAM_EXEC)		+= sram-exec.o
> > +obj-$(CONFIG_SRAM_DMA_HEAP)	+= sram-dma-heap.o
> >   obj-$(CONFIG_GENWQE)		+= genwqe/
> >   obj-$(CONFIG_ECHO)		+= echo/
> >   obj-$(CONFIG_CXL_BASE)		+= cxl/
> > diff --git a/drivers/misc/sram-dma-heap.c b/drivers/misc/sram-dma-heap.c
> > new file mode 100644
> > index 0000000000000..c054c04dff33e
> > --- /dev/null
> > +++ b/drivers/misc/sram-dma-heap.c
> > @@ -0,0 +1,245 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * SRAM DMA-Heap userspace exporter
> > + *
> > + * Copyright (C) 2019-2022 Texas Instruments Incorporated - https://www.ti.com/
> > + *	Andrew Davis <afd@xxxxxx>
> It's 2023 :(
>
> And this needs review from the dma-buf maintainers before I could do
> anything with it.

Yeah, agree. Thanks Greg.

It would be nice if you explicitly CC the maintainers for DMA-buf and 
DMA-buf heaps as well.

Of hand I can only find the version from 2020 in the LKML archives.

Regards,
Christian.

> thanks,
>
> greg k-h
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