[alsa-devel] ASoC driver parts probing order (MPC5200/MPC5121)

Wolfram Sang w.sang at pengutronix.de
Thu Oct 20 12:59:40 CEST 2011

Hi David,

> I am writing a AC97 ASoC driver for the MPC5121e SoC from Freescale. This SoC
> has almost the same PSC (Programmable Serial Controllers) as the MPC5200B, for
> which there already is an AC97 driver: sound/soc/fsl/mpc5200-ac97.c, so I'd
> like to extend that one to also support the MPC5121e.

Yes, this seems feasible. It has been done like this for the uart-driver, sadly
not for the spi-driver :(

> So obviously, it is supposed that the DMA driver
> somehow gets probed before the PSC driver, but I can't see where this is
> enforced. AFAIK, the order is fairly random, so it could be the other way

Check arch/powerpc/sysdev/bestcomm/bestcomm.c at the end:

/* If we're not a module, we must make sure everything is setup before  */
/* anyone tries to use us ... that's why we use subsys_initcall instead */
/* of module_init. */

while the mpc5121-driver has simply module_init() here. subsys_initcall() is
also often used for I2C host drivers to ensure client drivers can access them

> 1.- I can't test it on a MPC5200B, so therefor I need help.

I can do tests.



Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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