* Sleep-capable GPIO slave-selects on MPC52xx?
@ 2010-01-11 20:13 Bill Gatliff
2010-01-12 16:50 ` Bill Gatliff
0 siblings, 1 reply; 2+ messages in thread
From: Bill Gatliff @ 2010-01-11 20:13 UTC (permalink / raw)
To: linuxppc-dev
Guys:
A platform I have inherited utilizes a GPIO on an I2C expander chip
(MAX7314) as a SPI slave-select. I'm using the actual MPC52xx SPI
peripheral, not a PSC.
It looks like the current version of the MPC52xx SPI driver won't work
with sleep-capable GPIOs for slave-selects. In particular, it looks
like mpc52xx_spi_fsmstate_transfer() is an interrupt handler that calls
mpc52xx_spi_chipsel(), which itself calls gpio_set_value(). Or, at
least my kernel thinks so, since I get a barrage of oops-type output
screaming at me whenever I hit the SPI device. :)
Am I missing something, or is this a known (or at least now-identified)
limitation of the current mpc52xx_spi.c?
Thanks!
b.g.
--
Bill Gatliff
Embedded systems training and consulting
http://billgatliff.com
bgat@billgatliff•com
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Sleep-capable GPIO slave-selects on MPC52xx?
2010-01-11 20:13 Sleep-capable GPIO slave-selects on MPC52xx? Bill Gatliff
@ 2010-01-12 16:50 ` Bill Gatliff
0 siblings, 0 replies; 2+ messages in thread
From: Bill Gatliff @ 2010-01-12 16:50 UTC (permalink / raw)
To: linuxppc-dev
Bill Gatliff wrote:
>
> It looks like the current version of the MPC52xx SPI driver won't work
> with sleep-capable GPIOs for slave-selects. In particular, it looks
> like mpc52xx_spi_fsmstate_transfer() is an interrupt handler that calls
> mpc52xx_spi_chipsel(), which itself calls gpio_set_value(). Or, at
> least my kernel thinks so, since I get a barrage of oops-type output
> screaming at me whenever I hit the SPI device. :)
>
> Am I missing something, or is this a known (or at least now-identified)
> limitation of the current mpc52xx_spi.c?
>
So, nobody has any feedback on this? :)
Would using a threaded handler for the SPI interrupts be likely to work
here?
b.g.
--
Bill Gatliff
Embedded systems training and consulting
http://billgatliff.com
bgat@billgatliff•com
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