At Fri, 17 Jan 2003 01:04:40 +0100,
Pieter Palmers wrote:
>
> Finally I figured out how to enable the rear channel separately from the front
> on the creative labs CT5880 (= modified ens1371 as it seems).
great! thanks for your work!
> I'll describe the settings to enable this, but I'm not going to submit a
> patch, as I have noticed that I messed up my ens1370.c too much, and I can't
> get a clean version because CVS doesn't work. It's a minor change, so I
> assume it can be done by the maintainers.
>
> The whole thing is in three bits in the BASE+0x04 register (ES_REG_STATUS in
> the driver). These bits are bit27, bit26 and bit24
> There are three modes of operation:
> 1) No rear output: bit27=bit26=bit24=0
> 2) rear output is a mirror of the main output, but controlled by the
> 'surround' slider of the mixer. I assume the ens1371 mixes the two 'devices'
> and sends the mix to both MAIN and SURROUND DAC. This mode is selected by
> setting bit27=bit24=0 and bit26=1
> 3) independant rear (surround) and front output. Using the current driver,
> this has the strange side-effect that HW:0,0 becomes the rear output and
> HW:0,1 becomes the front. So HW:0,0 is controlled by the 'surround' mixer
> control, and HW:1,0 is controlled by the PCM and Master mixer
> controls.
this is because we are using DAC2 for the hw:0,0 and DAC1 for hw:0,1.
i'm not sure why it is.
Jaroslav, is there any drawback to use DAC1 as default playback?
(i know that the OSS driver uses this order, too.)
> To
> select this mode set bit27=bit24=1 and bit26=0. It seems that bit27=1 and
> bit24=bit26=0 is identical, but the windows driver clearly does the first, so
> why not? It works...
>
> front only, no rear: bit27=0 bit26=0 bit24=0
> rear mirrors front: bit27=0 bit26=1 bit24=0
> front & rear independant: bit27=1 bit26=0 bit24=1 (x?)
>
>
> I patched my driver by inserting the following code around line 1947:
> (I included two lines of overlap to make the location easier to find)
> =============================================
> outb(ensoniq->uartc = 0x00, ES_REG(ensoniq, UART_CONTROL));
> outb(0x00, ES_REG(ensoniq, UART_RES));
>
> #ifdef CHIP1371
> /* enable the rear outputs
> This seems to work
> ensoniq->cssr |= (0 << 27) | (1 << 24);
> but the windows driver does this, so let's
> also do it */
>
> ensoniq->cssr |= (1 << 27) | (1 << 24);
>
> /*
> Use this for mirror mode
> ensoniq->cssr |= (1 << 26);*/
> #endif
>
> outl(ensoniq->cssr, ES_REG(ensoniq, STATUS));
> #if defined(CONFIG_GAMEPORT) || defined(CONFIG_GAMEPORT_MODULE)
> =============================================
>
> Maybe there is a better place to put this? I don't know... I put it in the
> snd_ensoniq_create() function because I always want 4ch output, and I don't
> see the use of the other modes in an ALSA enviroment.
it would be better to create new controls, and changing the controls
via hook in the pcm configuration.
> Regards,
>
> Pieter
>
> PS: I'm also developing a driver for my Maxisound ISIS, where do I look for
> information on ALSA/linux driver developement? Does anyone have a 'template'
> ALSA driver?
there is a tutorial,
http://www.alsa-project.org/~iwai/writing-an-alsa-driver/index.html
the docbook source is found in alsa-kernel/Documentation/DocBook.
> Does ALSA support non-DMA audio transfer? I believe the ISIS uses this kind of
> transfers, but I don't know for sure yet. I know it's stupid design not to
> use DMA, but there is nothing to do about it I guess.
yes, but the implementation depends on the driver.
you can use tasklet for transferring the data e.g. via io-port
read/write.
Uros has been working on the ALSA SAM9407 driver, and IIRC, maxi ISIS
uses a similar (same?) chip. he might be able to help the development
of this driver.
ciao,
Takashi
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