Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Mon, 24 Apr 2017 12:55:21 +0200 | Subject | Re: [PATCH RFC 0/5] *** SPI Slave mode support *** |
| |
Hi Jiada,
On Fri, Apr 14, 2017 at 7:39 AM, Jiada Wang <jiada_wang@mentor.com> wrote: > On 04/13/2017 12:47 PM, Geert Uytterhoeven wrote: >> On Thu, Apr 13, 2017 at 2:59 PM, Mark Brown<broonie@kernel.org> wrote: >>> On Thu, Apr 13, 2017 at 05:13:59AM -0700, jiada_wang@mentor.com wrote: >>>> From: Jiada Wang<jiada_wang@mentor.com> >>>> >>>> v1: >>>> add Slave mode support in SPI core >>>> spidev create slave device when SPI controller work in slave mode >>>> spi-imx support to work in slave mode >>> >>> Adding Geert who also had a series doing this in progress that was >>> getting very near to being merged. >> >> Thank you! >> >> Actually my plan is to fix the last remaining issues and resubmit for >> v4.13. > > I noticed your patch set for SPI slave support, > (I am sure you can find out some of the change > in this patch set is based on your work). > we have similar requirement to add slave mode support to ecspi IP on imx6 > Soc. > > Our use case is to use spidev as an interface to communicate with external > SPI master devices. > meanwhile the SPI bus controller can also act as master device to send data > to other > SPI slave devices on the board.
That sounds a bit hackish to me. SPI was never meant to be a multi-master bus. While it can be done, you will need external synchronization (signals) to avoid conflicts between the SPI masters.
> I found in your implementation, SPI bus controller is limited to either work > in master mode or > slave mode, is there any reasoning to not configure SPI mode based on SPI > devices use case?
If you really need both master and slave support, you can use 2 subnodes in DT, the first representing the master, the second the slave.
Mark, what's your opinion about this?
Thanks!
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
| |