* RE: [PATCH v4] staging: gdm724x: Fix DMA from stack
[not found] <20210211053819.34858-1-ameynarkhede03@gmail.com>
@ 2021-02-11 13:28 ` David Laight
2021-02-11 13:52 ` gregkh
0 siblings, 1 reply; 2+ messages in thread
From: David Laight @ 2021-02-11 13:28 UTC (permalink / raw)
To: 'Amey Narkhede', gregkh, dan.carpenter
Cc: devel, linux-kernel, linux-usb
> Stack allocated buffers cannot be used for DMA
> on all architectures so allocate hci_packet buffer
> using kmalloc.
I wonder if the usb stack ought/could support a short bounce
buffer within the memory is already has to allocate?
For hci and lengths less than 8 the immediate data can be
placed directly in the ring structure replacing the data
pointer itself.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v4] staging: gdm724x: Fix DMA from stack
2021-02-11 13:28 ` [PATCH v4] staging: gdm724x: Fix DMA from stack David Laight
@ 2021-02-11 13:52 ` gregkh
0 siblings, 0 replies; 2+ messages in thread
From: gregkh @ 2021-02-11 13:52 UTC (permalink / raw)
To: David Laight
Cc: 'Amey Narkhede', dan.carpenter, devel, linux-kernel, linux-usb
On Thu, Feb 11, 2021 at 01:28:41PM +0000, David Laight wrote:
> > Stack allocated buffers cannot be used for DMA
> > on all architectures so allocate hci_packet buffer
> > using kmalloc.
>
> I wonder if the usb stack ought/could support a short bounce
> buffer within the memory is already has to allocate?
No.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-02-11 13:28 ` [PATCH v4] staging: gdm724x: Fix DMA from stack David Laight
2021-02-11 13:52 ` gregkh
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