Query regarding omap_set_dma_transfer_params()

Query regarding omap_set_dma_transfer_params()

[Pharaoh .]

Hi,

I am trying to configure the DMA channels in my ALSA driver.  Functions like


void omap_set_dma_dest_params(int lch, int dest_port, int dest_amode,
                              unsigned long dest_start,
                              int dst_ei, int dst_fi)
and omap_set_dma_src_params() are used for configuration.

What the last two fields i.e dst_ie and dst_fi mean here?

I think this has to do something with interrupts etc but not sure about it.
Also
I couldn't see those fields being populated anywhere in source (they are 0
everywhere).
I am referring 2.6.19-omap1.

Also, I think that these are unnecessarily exported, since the function
omap_set_dma_params()
is already exported and it calls the above mentioned functions.  And
normally the sequence of
configuring the DMA channel is like

-set src params
-set dest params
-set transfer params

-pharaoh.

Re: Query regarding omap_set_dma_transfer_params()

[Pharaoh .]

On 6/11/07, Pharaoh . <pharaoh137@gmail.com> wrote:
> Hi,
>
> I am trying to configure the DMA channels in my ALSA driver.  Functions like
>
> void omap_set_dma_dest_params(int lch, int dest_port, int dest_amode,
>                               unsigned long dest_start,
>                               int dst_ei, int dst_fi)
> and omap_set_dma_src_params() are used for configuration.
>
> What the last two fields i.e dst_ie and dst_fi mean here?
>
> I think this has to do something with interrupts etc but not sure about it. Also
> I couldn't see those fields being populated anywhere in source (they are 0 everywhere).
> I am referring 2.6.19-omap1.
>
> Also, I think that these are unnecessarily exported, since the function omap_set_dma_params()
> is already exported and it calls the above mentioned functions.  And normally the sequence of
> configuring the DMA channel is like
>
> -set src params
> -set dest params
> -set transfer params
>
> -pharaoh.
>

I found it.....

struct omap_dma_channel_params {

----

----
int src_ei;             /* source element index */
int src_fi;             /* source frame index */
int dst_ei;             /* source element index */
int dst_fi;             /* source frame index */

------


}

-pharaoh.

Re: Query regarding omap_set_dma_transfer_params()

[Tony Lindgren]

* Pharaoh . <pharaoh137@gmail.com> [070611 08:02]:
> Hi,
>
> I am trying to configure the DMA channels in my ALSA driver.  Functions 
> like
>
>
> void omap_set_dma_dest_params(int lch, int dest_port, int dest_amode,
>                              unsigned long dest_start,
>                              int dst_ei, int dst_fi)
> and omap_set_dma_src_params() are used for configuration.
>
> What the last two fields i.e dst_ie and dst_fi mean here?

See dma.h, ei = element index and fi = frame index. Some of these are
documented in the 2912 TRM pdf.

> I think this has to do something with interrupts etc but not sure about it.
> Also
> I couldn't see those fields being populated anywhere in source (they are 0
> everywhere).
> I am referring 2.6.19-omap1.
>
> Also, I think that these are unnecessarily exported, since the function
> omap_set_dma_params()
> is already exported and it calls the above mentioned functions.  And
> normally the sequence of
> configuring the DMA channel is like
>
> -set src params
> -set dest params
> -set transfer params

Well you can do it both ways, sometimes you just want to update the
source or destination between transfers.

Tony