[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 at ti.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 at ti.com>
> 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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