Re: [PATCH] spi: imx: Don't expect DMA for i.MX{25, 35, 50, 51, 53} cspi devices

[Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>]

Hello Martin,

On 15.05.2024 21:26:17, Martin Kaiser wrote:
> Thus wrote Martin Kaiser (martin@xxxxxxxxx):
> 
> > > However this breaks SPI transfers, when I try to read out an MRAM I get:
> 
> > > 	root@ecu02:~ hexdump -C /dev/mtd4
> > > 	[   71.813807] spi_imx 43fa4000.spi: I/O Error in DMA TX
> > > 	[   71.819173] spi-nor spi0.2: SPI transfer failed: -110
> > > 	[   71.829129] spi_master spi0: failed to transfer one message from queue
> > > 	[   71.843962] spi_master spi0: noqueue transfer failed
> 
> > > So it would indeed be interesting if you ever managed to use DMA on
> > > i.MX25.
> 
> > I believe so. Looking into my notes from 2016 (when I last tried this), I got
> > the -110 error when the SMC bit in CONREG wasn't set. But this should now be
> > done in mx31_prepare_transfer if DMA is used...
> 
> > I'll try to set up a test some time next week.
> 
> I can now reproduce the dma tx error. My test board uses a dummy spidev device
> on cspi1 and configures loopback on the cspi1 controller (disabling loopback
> makes no difference).
> 
> I'm relatively sure that this setup did work back in 2016/17.
> 
> Commit 24bb244e02a6 ("ARM: i.MX25: globally disable supervisor protect") was
> required before any DMA transfers started working on imx25. As far as I can
> see, this code is still present.
> 
> I'll look into this a bit more as time permits.

have you found the time to look into this?

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
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