linux-kernel - Re: [PATCH v3] misc: sram: Add DMA-BUF Heap exporting of SRAM areas

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Date:   Thu, 13 Jul 2023 21:28:47 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Andrew Davis <afd@...com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Christian Gmeiner <christian.gmeiner@...il.com>,
        John Stultz <jstultz@...gle.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linaro-mm-sig@...ts.linaro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] misc: sram: Add DMA-BUF Heap exporting of SRAM areas

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@...com>
> ---
> 
> 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@...com>

It's 2023 :(

And this needs review from the dma-buf maintainers before I could do
anything with it.

thanks,

greg k-h